My very unqualified opinions. The ABS light is either a wheel sensor or the OVP relay. I don't know how to diagnose between the two. AC system... charge the AC system with oil freon with UV dye in it. See if it holds the charge and if not, from where it leaks. I think everyting but replacing the evaporator is manageable. I would presonally replace evey fuse in the vehicle. They may look OK but they're prone to fail without visible signs. Dealer's parts department is the place for those. If you call the Dealer's parts department and tell him the screws you want, he should have them for about $1 each. The dealer can pull up on computer an illustration of every single part that makes up that car. Even if you don't buy parts from the dealer, the information and advice the dealer can provide will be invaluable to you. Just stick with the parts guys and stay away from the "service adviser." Clean and lube the heck out of the antenna. If it's moving at all, it seems like it's working. After that, you're looking at new parts. Are you keeping the OEM stereo? No clue about the heater thing. Check out startekinfo.com. Not sure if it goes back to the M103, but if not Mercedes publishes hard copy manuals for the 124 chassis and 103 motor. I bet you could get them at the library. Very helpful. Sign up for a day and print what you need. If you computer son figures out a way to hack in, please let me know. A new tube and the necessary hardware to connect it shoud be cheap at the dealer. If you find a better place to get OEM little parts like that, please let me know. Enjoy.

__________________
Michael

1988 300 SL (5 Speed)
1994 E320 Wagon
1997 C230