as for the seat, i would check the wire underneath it, its just a 2 wire clip. if one seat works the other should too because im pretty sure theyre on the same fuse.
as for the windows, if you hear a click in the door when you move the switch but the window wont move its the motor. trust me, they go out if you blow on them sideways. all 4 of mine have gone out a one time or another and both my dads front ones have. as far as i know the window switch is exclusive to the park in this body style. but a junkyard and big pockets will help with that.
the rack/pinion is super common on them too. mines on its way.
the radio is interchangeable as long as you get it out of a park. other buicks might trigger the theftlock. but speaking from experience i got a spare out of an 05 ultra at a junkyard and it works fine in my car.
if he needs help doing any of this let me know. ive done it all to my car thanks to the help from people on this forum. im about 45 mins east of the city just on the other side of gary.
6000k headlights, LED license plate fog lights, tinted taillights and to top it all off, 2 12" air horns!
the gf:'00impy 3.8, every option. COTM July 2013