I know Wikipedia is not the best or most reliable source of information, but all its numbers can be confirmed by individuality checking each nations aid from the US with a quick Google search, with the exception of Afghanistan which seems to have conflicting back up information and that seems to be mostly from what different people or groups consider aid going to Afghanistan but it seems most websites are putting the yearly amount of aid at $5 billion, with a few going it seems as low as about $2.5 billion and others as high as $12 to $16 billion.
If you honestly think 1 nuclear weapon can destroy Iran you are just delusional about how powerful a nuclear weapon is and how they are designed. First the most powerful nuclear weapons only have blast radius of about 10 km, unless thermonuclear weapons are used, but even then the blast radius of the largest thermonuclear weapon ever used was 58 km but due to its size and weight it is not a viable weapon to be used so the blast radius of thermonuclear weapons that are actually viable weapons is about a blast radius of 35 km. So even if Israel would use a thermonuclear device on Iran the amount it would need to destroy Iran is just a ridiculously large amount of thermonuclear weapons.
Second your understanding of fallout from nuclear and thermonuclear devices is just plain wrong. While the first two atomic bombs used where not that clean in terms of fallout each successive generation of nuclear weapons became far cleaner in terms of fallout. They where made to reduce fallout for a very simple reason, the more fallout a nuclear weapon creates, the less powerful the blast of the nuclear device was because that is less of the nuclear material that is radioactive being used to create the blast. With current nuclear weapons even though they do create radioactive fallout the amounts they create are far less then the ones used in WW2. As for thermonuclear weapons they create even less fallout then nuclear weapons because the main fuel for the thermonuclear weapon is not radioactive, actually the only radioactive part of a thermonuclear weapon is the nuclear device that is used to start the fusion process and that only requires a nuclear device about the side of a tactical nuclear weapon so the radioactive fallout they produce is even less then that of current nuclear weapons. The only type of nuclear weapon that produces enough fallout that you seem to be predicting from a nuclear strike is a neutron bomb.