1) probably a bad combo switch. Pushing in the end knob to engage the wipers twists the end knob to the intermittent position. It wipes continuously whch the end knob is pushed in then returns to intermittent until you turn it off.

2) would be my guess

3) hot air for the rear cabin comes from under the front seats. Close the rear vent manually if it gets too cold. Welcome to MB ACC

4) I don't think the chain can squeak

7) check the plastic fittings on the cam towers that squirt oil on the cam lobes. When these go, the cam follows shortly.

Sixto
95 S420
87 300SDL