1991 Buick Park Avenue Electrical Gremlins

I have a 1991 Buick Park Avenue that seems to have some electrical issues. There is an open connection somewhere that allows the battery to bleed down unless the fuse that controls the power seats is removed. The interior lights do not come on when the doors are opened, but they do come on when the car is placed in reverse. Last but not least, the car has the digital a/c and heat. The a/c is out due to a faulty compressor, (I am replacing that) the heater is comes on only on high, and sets its temperature at 151 degrees. You get "high and hot" or "off and cold" in the winter; there is no in - between. As a footnote, there was an incident where a tree limb fell on top of the car right over the driver's seat. It was not a big dent, but had to be repaired in a body shop, consequently they had to replace the headliner. Are these things related?