electrical diagnosis please (96 camry)

Hey all. I was hoping someone would be able to tell me what's wrong with my fiancee's 96 camry... All these issues have begun in the last 3 months:
- dome light keeps blowing out
- power door locks are on the fritz.. sometimes they work sometimes they don't.
- rear pass side power window doesn't work.
- lighting behind the center dash (heat/cool/fan) stuff is out.
- now... newest issue, the stereo (aftermarket Pioneer 2 years old) doesn't work. Some buttons will power it up for 3 seconds but only the clock... then it turns off again.

It would seem to me that all of these issues are related to one electrical problem, but I know little about cars and less about electrical.

Thanks
Matt