Please put your car in your avatar or signature.
1) To stop any diesel, starve the engine of air or fuel. sounds as if you have an air leak somewhere. Does the stop lever work? Does the car shut off with the key? If so, and the lever doesn't work, apply vacuum to the shut off actuator (control).
Check here for parts numbers:
Mercedes-Benz Teilekatalog (Ersatzteile online)
3) Normal, see first attachment and third, maybe better pic.
4) Depends on your car, my transmissions are as the second attachment.
5) You may have nailing issues, run a diesel purge, well, if you can get some, fluid you know. Have the injectors pop tested, not easy in your area.
6) Some, but it seems excessive, any other transmission issues?
Also, consider starting a specific thread, this one is getting long in the tooth and I'm not going to read the whole thing.