Here's my 2 cents worth for a few of your issues:

1. While the seat is forward, take out the bolts at the back of the rails. You'll still need to move the seat back to remove the front ones, but in case it does go back and not forward again, you're 50% done. All four need to come out to remove the seat.

3. I once has a 1975 450SE with a shot sunroof motor. I discovered that the same motor is used for the windows, it just bolts to a different gearbox. Check yours, and you might find a used window motor easier and cheaper, if that's the problem.

5. Check for a little black plastic lever at the headlights. These are designed to flip the lens up/down to compensate for heavy loads in the trunk.

7. Take the exhaust in to a muffler shop and have it welded up. Yes, you can weld stainless with a mig welder using mild steel wire (which will rust, but that's OK for a quick fix).

Antenna, if it's a Hirschmann, can easily be removed and rebuilt. Well worth while. May just be a dirty mast. Remove the liner to expose the unit. The top in the fender is either in a rubber grommet or has a nut mounting. Undo the nut, if so. Then, undo the bottom mount bolts. Remove radio lead and ground wire, unplug connector. If rubber grommet, just pull down and unpop the unit. When you get it out, repost on the audio forum and search under 'antenna'.

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1986 560SL
2002 Toyota Camry
1993 Lexus