My girlfriend and I recently bought a 1986 Volvo 760 Turbo with 136k miles. Mechanically, the car is quite sound. There are some superficial things I would like to deal with but without spending a lot of money. I typed a list below. Any help anyone out there could offer would be greatly appreciated.

1) The dash has a few cracks in it. Is it worthwhile to buy a repair kit at an auto parts store? Or will it look poor enough that I should just live with the cracks?
2) The leather seats have 3 seam separations (1-1 1/2 inches) that an upholsterer advised against repairing, as the repair would not last long. Would generic cloth seat covers be suitable?
3) The back stereo speakers do not work, unless you adjust the fade fully to the back speakers. Then, if you crank up the volume you can hear a very soft and distorted sound from the back speakers. (I have the AM/FM/Tape/Equalizer)
4) The overdrive button on the automatic shift does not shut off reliably when the button is pushed. It has even gone on after hitting a bump.
5) The body is in very good shape. No rust, no dents, but the finish seems dull (silver paint). What could I use to shine it up a bit?
6) There is a low whistling sound coming from the heat vents.
7) The driver seat does not heat. Is this easily fixed?