I wasnt sure about this so I did a quick search. The Germans promised to support Mexico's claims in case war errupted between America and Germany.

Ranger, if you read my earlier post on the subject, you can see that I agree on the coal-bunker explosion as the cause of Lusitania's sinking.
However, I must disagree with you about the military cargo. I don't know about the documentary on Discovery Channel you saw, but a cargo of rifles, rifle amunition, shrapnel shell cases and fuzes* is recorded on the ship's manifest, albeit not in the "official" one filled before the ship's departure from New York, but on a second, "suplementary" one, filled by the port officials while Lusitania was 2 days into her trip. This was probably done for securty reasons, so that any potential spies would not know of the actual cargo she was carrying. Anyway, despite it's military nature, the goods she carried were of a rather inert nature (rifle cartriges are "unexplosive in bulk quantities" and tend to burn quietly rather than burst all at once), so if the torpedo had struck the cargo hold instead of the coal bunker, it is likely that no secondary explosion would have followed, and a lot more lives would have been saved.
The whole "German monsters sinking unarmed merchantmen" was mostly propaganda, because the captain of the Lusitania had orders to attack by ramming any U-boat that tried to stop her by ordering her surrender (there have been recorded incidents of such rammings being sucessful before the incident involving Lusitania), so I can certainly understand the reticence of Kapitanleutnant Schwieger to surface U-20 and signal the ship to stop...
Not to mention the fact there is a controversy involving the presence of at least two 4.7 inch guns on board Lusitania to be used "if the need arises", but since no material evidence about this armament exist beyond word of mouth, I tend not to take that into consideration.

*To be more specific, "4200 cases of Remington .303 rifle cartridges, a thousand rounds to a box, 1248 cases of 3 inch Shrapnel shells filled, eighteen cases of fuzes", and I recomend you read the article 'Riddle of the Lusitania" in the April 1994 issue of the reputed National Geographic Magazine, where they have photographs of some of the fuzes lying scattered at the wrecksite.

Why was there a food shortage in Germany? In terms of food, Germany was never self-suficient and relied masively on imports, and since the British Grand Fleet was busy confiscating any cargo bound for Germany, including food and medical supplies, this was the logical outcome. It had nothing to do with the quality of the work in the field, and soldiers ate little better than the general population.

You can read my oppinions on the matter in my earlier posts. IMHO, Wilson was never anti-war, and was just waiting for the most advantageous moment to step in and "save the day"- for it's implication in the Great War, the USA was awarded war reparations. Of course, he still had the problem of convincing Congress to do his bidding, but that was solved with a bit of shrewd media manipulation, as well as that collosal blunder made by Zimmerman on March3, of actually confirming that the intercepted telegram was genuine...

Well, the vast majority of soldiers were actually used as cannon fodder, so inexperience was not a problem... But you are right about this- the initial results of American troops in battle were mediocre at best, and both common soldiers and officers had to embark in a cras course of trench warfare 101 before being able to cope with the difficult conditions on the Western Front. However, as with the Soviet Union in WW2, quantity was more important thean quality, and it was the overwhelming mass of fresh US soldiers, coupled with the mounting pressure on the home front (riots and demonstrations regarding the lack of food) as well as ad-hoc strikes in the german personnel (the famous mutiny of the Hochseeflotte, for example) that finally brought Germany to its knees.

Well, I never said ramming from the part of Lusitania would be practical, but that was the order given to all British captains, and the Germans knew it. Albeit ramming from a ship the size of Lusitania seems unlikely, in the Admiralty fleet register she was marked as an armed auxiliary cruiser from December 1914 onwards, end even if her main armament of twelve 6-inch guns had not been installed yet, there was no way for the German commander to have known that. He just identified the ship as “either the Lusitania or Mauretania, both armed cruisers”, and shot a torpedo. He certainly wasn’t going to expose his sub to fire just to see wherever Lusitania was indeed armed.
In fact, there is an incident happening a few months after Lusitania that proves that submarines were at risk from traps set up by the British:
"On 19 August 1915 the British freighter NICOSIAN, hauling mules from New Orleans to England, was stopped by U-27 about seventy miles from Queenstown. The submarine fired a warning shot and the crew abandoned ship. The British ship BARALONG, ostensibly a cargo ship but in reality a Q-ship, came on the scene, flying an American flag (this is generally regarded, perhaps surprisingly, as legitimate ruse of war, provided the ship's true colours are displayed before she opens fire). When about a hundred yards from U-27 BARALONG raised her British colours and opened fire, sinking U-27. About six Germans, including the captain, were shot in the water. About six others boarded the deserted NICOSIAN. Royal Marines boarded NICOSIAN with orders to take no prisoners, and the defenceless German sailors were hunted down and shot. Although early British accounts denied that an atrocity had occurred, the incident was witnessed by neutral American mule-handlers from NICOSIAN who had no reason to invent such a story. [Bailey and Ryan, pp. 50-51; Devlin, pp. 413-18]"
Also, I believe there was a notion of tactics involved - Lusitania was travelling at almost 18knots when she was torpedoed, and her maximum speed was 21. U-20's speed was 15.4 knots on the surface, and 9.5Kts submerged, but she could only keep that speed up for one hour, before her batteries ran out. So in my mind, it's clear that had she known U-20 was there, Lusitania could have easily outrun her, so the only way Schwieger could have sunk the liner is a surprise attack.
On the other hand, Kapitanleutnant Schwieger was known to be an extremely cautious man, even bordering on the paranoid, as wel as pretty ruthless, since he earlier attacked a ship flying the Norwegian flag, as he assumed it to be a British merchantman in disguise.

You are forgetting, of course, this was WWI we are talking about. Wireless telegraphy was still in it's infancy and the only reliable way to communicate between the "old" and "new" continents was by the Trans-Atlantic Telegraph wires, and it was by this means that spies had to relay intelligence back to the Germany.
But anyway, the ruse of the "fake manifest" is quite simple, and has a psychological reason: a ship's manifest is a document prepared prior to a ship's leaving port, and aids in making sure that all cargo bound to go on that ship has actually been loaded, as well as aiding the port authorities keep track of what has been sent where.
And, of course, it's at this time that any spy would want to check the ship's manifest to see what it's carrying. However, were you to have cargo you do not wish other people to know about, but still wanted to keep track of, it's easier just to make an incomplete manifest when the ship departs, then add the missing items on a second, "supplementary" manifest, a few days later after the ship has sailed, because it's pretty unlikely that anyone will come and rifle trough the archives once the ship in question has left port, just in case there might have been items that were omitted from the original loading manifest. Add that ruse to a harbour where hundreds of ships load and unload daily, and it makes a very remote possibility for anyone to realise a new manifest has been drawn up, secure a way to transmit it over the Atlantic, have it reach German Naval HQ in time to mobilize any u-boats in the area to intercept the ship, all in the short three days needed for Lusitania to complete her journey...

I hope this answers your question:
"In 1850 Germany exported food-stuffs and raw materials, and imported manufactured goods; now [c. 1905] her principal exports are manufactured goods, and her imports are raw materials and foodstuffs. In this period she has changed from an agricultural to a manufacturing and commercial nation."
E.D. Howard, The Cause and Extent of the Recent Industrial Progress of Germany, 1907

The problem was that same with Romania after WW2: the rapid industrialization and urbanization of Germany in the late 19th century meant that less and less people were available to work the fields, so the agricultural production dwindled, while the industry was on the rise, and this was even before WW1 started.
As from the supplies coming up the Danube, where were they supposed to come from? Austria-Hungary, who had a food shortage problem of her own? Russia, that was at war with the Central powers? Romania, that entered the war on the side of the Entente? Not to mention the fact I find it highly implausible for anything bound for Germany to have passed trough the Romanian controlled section of the Danube, especially foodstuffs.

Also, about 135 ships of various sizes had their cargo confiscated by the British monthly in 1916, and as may of 800000 German civilians are known to have died from starvation in the last three years of the war. Put two and two together, and you get…

I don't remember making any statement about medical supplies, but I must tell you they lacked on both sides of the front, because the medical facilities that, before the war were at least adequate if not sufficient, were now under tremendous strain. And indeed, it's the Germans that managed to get the best medical services of the war, partly because of their better organization and the quality of their medical staff.

Like I said, he had a problem with the US Congress. Unless Congress agreed that the country should go to war, any action from his part would have been seen as highly suspect and inappropriate, and nothing would have been more stupid than try to prepare the American economy for the conflict before an official stance was drawn up, as it would have been a dead give away on his intentions to everybody, especially the Germans.
Oh, and by the way, his name is actually “Woodrow”.

that is very debatable. while i agree that Britain is the least to blame, the other participants actively pursued the path to war.

this doesn't explain the mobilization which they ordered first. just as A.H. had backing from Germany (which could be summerized into "whatever you do, if Russia goes to war against you we go to war against Russia", which they were bound to do by treaty anyways) Serbia had backing from Russia where the panlavist movement was in full swing (and the czar the chairman of the society for perpetuating panslavism).
you can go ahead and question the right of existence of a compulsory multinational state like A.-H. but, by the standards of that time, letting anyone to get away with the assasination of a heir would be the nail in coffin of that monarchy. so for A.-H. the affair was existential and same for Germany who could not afford to lose the only (politically) reliable ally.
then we can go ahead about french revanchist claims (debatable or not) and we have a recipe for desaster which, Germany didn't encourage much beyond reasonability and other's didn't care to undertake steps (to a similar degree of reasonability) to avoid a war.
the result is *BOOM*.

the same can be said then about France&Britain in 1939.

the imperial german gov. assured A.-H. of their total support in this affair.
if was clear that if Russia will mobilize, then Germany will do so too. from then war is inevitable.

then why did they mobilize on july 28th against A-H?

the german chancellor was actually against war but he issued a statement that the russian mobilization (or lack thereof) would decide wether germany would mobilize (and declare war).
who exactly did hold back what from the Kaiser?

france was bound by treaty to aid russia in case they would have war declared upon themselves. which was again obvious in case russia would wage war against A-H.

the "black hand" however was a serbian panslavistic organisation. of which he was part of.

on this we actually never disagreed. the very moment was determined by the assasionation. other than that it was not a question of "if" it was a question of "when", given the political environment and maybe the "Zeitgeist". but the responsability of the nature of this environment lies with pretty much everybody (albeit to a lesser degree with Britain).

again that depends. yes, nazi germany annexed austria. but austria was forbidden of joining the reich in 1919 even though a referendum showed overwhelming majority. yes germany invaded czechoslovakia. but the situation with the sudetenland was similar with austria.
yes germany invaded poland, this time not only to recover "lost" provinces but to completley destroy it (lebensraum). but with the large support of the soviet union which felt threatened by the "capitalist world" since its formation and whose aim was to "encourage" any war between the "capitalist powers" to secure its existence (a doctrine repeated throught pretty much every congress of the CPSU in the 20ies and 30ies).
also the framework for WW2 was laid at Versailles and poeple like Hitler used it to gain power.
the peace of 1871 left problems unsolved. so did the peace of 1878. and the peace of 1919. those whose problems were left unsoleved prepared for a follow-up war.

exactly. but the same thing you could say about Germany. that's the problem if you commit to an alliance. and france wasn't exactly rejecting the idea of a war with Germany. the was never a "cool down" message to the czar just like there was no german "cool down" message to A-H.

absolutely correct. if my posting implied something else, then it's due misformulation which is entirely my fault.