I wouldn't suggest that eliminating foreign aid would get rid of current issues - my own country seems to think that spending billions in aid as a means of "soft power" is a better use of resources than keeping our Harrier jets, for instance. Not being an expert on foreign policy like our esteemed Prime Minister, I tend to differ, but then again I'm a cynic and see most aid money going into Swiss accounts of various third world leaders anyway.
On WWI, I think you're half right - but the threat of German attacks on Atlantic shipping was certainly a factor, and it was in America's interests to keep trade going even at the cost of war.
Unfortunately, I see the current Iran policy leading inevitably to a war - whether the economies of the West will be strong enough to survive the inevitable oil crisis is debatable, and I worry that the response of governments will be to impose totalitarian rule on what will be an increasingly angry citizenry.