On getting the screws back in, it just takes practice

Or what you can do is put a piece of tape over the head of each screw to hold it in place, stack the washers on each screw, put the drive on top then take the tape off each screw one by one screwing each in by a couple of turns, once you have done this for each screw simply screw each one in all the way

I have done this way to many times with xbox 360's back when I used to repair them....