I haven't seen anyone reply to your post so I'll offer something.. I've driven a diesel Benz since 1978 (285,000 miles, never opened the engine) and I've had both problems you mentioned. Regarding speedo, suppose you already know not to go to dealer.. high $$$.. a good speedo shop, OR a seasoned independent Benz mech can fix it.. problem lies in a small gear in the odometer, it is replaceable at a moderate cost... most of it is the labor to access it. As I recall my total bill was under a $100 about 10 years ago at a speedo shop, then again 2 years ago at a local (Denver) mech it was about $60. As for the window, it SOUNDS like the window regulator. The price of those varies by model and whether it is front or rear.. but not terribly high.. between $80 and $150 on ones I've run across. To access it my 190E and 300CD the bottom and sides of the door paneling are held in by "pop" fittings and one or two large screws recessed under the armrest. Once those are opened the entire panel will lift up about an inch and can be removed. (haven't tried it in my 350SDL) You will see some aluminum arms that hold the window and some gears attached to the motor. You might try lubricating moving parts with a heavy grease and see if that helps. Failing that, a Benz mechanic can do it in about half an hour or so. Again, I never go to dealer shops. Their "by the book" pricing, lack of access to the guy doing the work, and difficulty talking to someone who REALLY knows the car tends to keep me away.
Congrats on your new Benz purchase though, enjoy the car, CHANGE THE OIL at 3k miles, and find a good independent guy to work on it when needed.