This is how the panel comes off
PeachPartsWiki: Replacing the Front Door Panel
The remotes come from MB code to your car, they need to see the car and you w/DL about $200, there is nothing you can do to escape. The shop can remove the existing code.
I would drain refill brakes, trans etc.
The roof top antenna is for the CTEL and the GPS puck is in the cover, MB wants $100 or so for a gasket and antenna cover. do a search on 2108270031KIT, which will get you a gasket and rubber whip cover.
The sticky buttons have been cleaned by some people, MB sell a replacement, few hundred.
The standard bars are flimsy, the roof itself is also flimsy. MB crossbars with locking cables are pretty ugly, expensive and the adapters are also expensive. I have experienxce with both, and ws able to sell one set (MB Thule type) I purchased and have used the flimsy bars that were standard with the prior to 01 cars and would not attach any thing heavy the soft carrier bag would work.
Check the bottoms of your doors for rust.
The car is pretty good, I have 80K since new, with no major issues other than window regulators, engine pulley, directional switch.
It is not what my 85 wagon was, but it is better than my short lived ML.