1. The clips that hold the headrest post to the motorized riser are broken. You might be able to fix them. Otherwise it's a US$17 part. Remove the two screws at the corners of the bottom edge of the rear cover of each front seat. Then pull down and remove the cover. It should be obvious how the headrest mechanism works.

2. There should be buttons for the sunroof, rear dome light, hazard flasher, rear headrest collapse and antenna. There might be other buttons depending on options.

3. Maybe the arm that pulls down the little deflector as the sunroof closes?

4. There's lots of info in the archives. If you have a lot of repairs to do, it's well worth getting the MB shop manuals available on CD from FastLane (see link at the top of the page). You might be able to find printed manuals on eBay or some book seller.

Sixto
95 S420
87 300SDL