For removing door cover:
I have a 190E, so the process probably isn't identical (given the IMO lesser quality on the C-class it may be easier). There's a plastic cover that goes around the top of the door closing handle. Pry off with screwdriver and be careful not to damage. Then undo the bolt behind with a 10mm screw.
There's also a screw at the back of the door holding a piece of plastic around the door's catch. Undo, and now the door will be loose. The outside of the door cover is held on by clips. Lift up door cover to unclip, it should separate from window seals too. At some point you'll need to unhook the door opening lever from the bar going back to the lock.
For me, that's it.
2.5-16v 1990 90,000m Astral Silver
2.0E 8v 1986 107,000m Black