When the FED is buying US bonds through QE2 they push the other bond-buyers into buying other things, instead of the bonds the would have bought, had the FED not distorted the market. This pushes prices up for other asset classes. There's excess liquidity desperately looking for ROI. The money has to go somewhere.
So here's to hoping there is no QE3, ya?
What you're saying doesn't make any sense whatsoever.
FED and the other private banks are not stockpiling US dollars in their own accounts.