Problem 1: Yes, the screws tighten down on to the backplate and not the board, this is normal.
Problem 2: As far as i'm aware there is no easy way to separate the fans and pump.
problem 3: Yes, from around 1480-1525rpm on mine there is a distinct drone. I have mine set to operate between 1550rpm and max rpm. Hardwarecanucks mentioned the drone in their review i think.