The FEDs mandates are simple, they are to simply keep the Pozi scheme going, re-elect whatever bozo is in the whitehouse by keeping people happy by giving them money and to make themselves indispensable.
The fist mandate is self explanatory. The second is easy to figure out, under bush. They print money to help the war effort and make rich guys even richer, under Obama, he prints money to give to the poor to get them motivated to vote.
By making side deals with banks and creating convoluted instruments, keeping data like M3 and real gold reserves secret, and creating bust cycles makes them important.