Agree bimmerforums and pelican are both great sites. If you son bought an E30, make sure the first thing he does is replace the timing belt! They are interference engines and when that baby goes, the repair will exceed the value of the car instantly, unless he bought an M, in which case, they don't have a timing belt...but I digress.
Also, if his power windows go out the repair is pretty easy, 1) if you push the switch and the interior/instrument lights dim, then the motor is stuck/bad. Hit the door panel in the center front...where the PW motor lives while pushing the switch, that will usually unstick it. If the lights don't dim, then it is usually the switch contacts. The easy fix is to take the switch apart and solder a little ball on the contacts. Finally, the PW switches illuminate on that model. If they don't, Radio Shack sells a small 12v replacement light for cheap, just disassemble the switch and remove and resolder a new bulb!