The "good" news is that these are all relatively common problems that you can find discussed if you do a search on this forum.

1) I believe there is a circuit board in each tail light. I've not experienced this but it was discussed just this week.

4) Bad reception is probably a poor connection at one end of the shielded cable that runs from the radio to the antenna, or physical damage to the cable or the antenna. If you pull the glove box so you can access the back of the radio, or pop out the covers to the left of the radio and pull the radio out, a little trial and error with a coat hangar antenna should trace the problem.

5) Speakers going in an out is typically the balance/fader control in the radio. Those things were chronically defective and resulted in a LOT of '90+ radios getting pulled out and tossed within the first 5 years of car's life. If you have an original radio in a '92, that is relatively rare. If you have some tuner cleaner spray, pop out the radio and pull the cover and give that potentiometer a good soaking, followed by a lot of physical abuse (twisting, pushing, pulling on the knob) to clean it up. I had to do that to my '91 once a year from about year 3 to year 7. After that, it seemed to clear up and has worked OK since. I bought my '90 used, so it already had a different radio in it when I got it.