Nobody likes the IRS. I believe, and I could be mistaken, that you're still confusing the prebate with some form of "welfare". When you get a refund check from the IRS when you file your taxes (if you do, myself, I always end up paying, but that's a rant for another thread), do you consider that to be "welfare"? The difference between a "refund" check, and the "prebate" check is all in when you get it. If it'll make you feel any better, look at it this way, with the FairTax, the first "prebate" check you get will be a "stimulus check" like most people got this year, and every check after that is a refund check (like you currently get once a year, only now, you'll be getting it every month) for all the taxes you overpaid.
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Lacking a Constitutional Amendment where by Congress would be REQUIRED to make a formal declaration of war, I don't have the answer. Also, it would be necessary to ensure that none of our treaties allowed for any intervention in the affairs of a foreign nation. The problem with most of this is that, other than purely national defense, most of our wars have been about ensuring our access to free and unfettered international trade, whether by preemptively stopping a threat to that trade, or by engaging once the threat has manifested itself.
As I mentioned elsewhere, attaching our economy to any tangible assert in this day and age is extremely dangerous. Looking at your gold example, assume for a moment that we are able to corner the world market on currently available gold; what happens if 2 years from now Luxembourg suddenly discovers the largest gold deposits ever discovered right under their own feet, and they start producing those deposits and flood the market? Our economy could tank over night, and unless we invade Luxembourg and seize their mines, there's nothing we can do about it.
No, at this point, having our economy tied to our own productivity as a nation is the only way to ensure the long term stability of our economy. There's also the fact that there's so little gold in the entire world, that at the current exchange rate, it doesn't equal 2 years of our budget, much less the rest of the world, which would require a total revaluation of the entire worlds net worth! That alone would not only wreck the worlds economies, but would probably lead to massive wars from the fallout.