I think they receive this power upon initiation to skull and bones ( speaking of American presidents here only ), after which thy must achieve certain goals during they're presidency. Often how they achieve it is up to themselves, as long as they achieve it. I really don't want to dwell on the whole hierarchy of the power of the elites because it is a very extensive subject. It's not as simple as rich men above, puppets in the middle and sheep below. And it isn't even the point. They're power is derived from controlling the masses through fear and money... right? Well, they don't do the dirty work themselves... that's what the puppets are for. Puppets regulate the masses and obtain the power, the rich men themselves don't have any other leverage besides money.

And no i'm afraid i don't know what his salary is :P But if he were working WITH the bank mobsters and the federal reserve, then he could have money printed for himself at any time of the day.