A) Going back to the gold standard is dangerously limited. Like the good doctor suggested, we should go to a basket of currencies, or better yet let many currencies compete.
B) You're right, economically, one ounce of gold could be enough money for the whole world to trade if we could just separate the molecules and keep track of them better. It's still dangerous putting all your eggs in one basket though.
C) Strict constitutionalists will say that the treasury should be in charge of regulating the money supply and adding to it as they see fit. Rising and falling with the GDP would make sense if they do so.
Of course, AnCaps like myself think that it's a mistake to ever let a government touch your money supply at all. The free market should determine EVERYTHING.
D) There are so many great arguments against that horsecrap it's almost common sense to most anarchists of any school. The best way I know to put it is that monopolies lose their teeth in the free market; only a government has the power to make monopolies undesirable. The fact that people speak about monopolies as being a bad thing is a testament to the sheer evil of governments themselves!
HONEST RON 2012!