1) Just redo it yourself, unless you find one in good shape on ebay or r3v.
2) I remember replacing all this sensor crap on my black e30 and the light was still on. In my frustration after all that work + money for the sensors, I just took out the light. Some people bridge it, but I thought the light removal trick was easier
3) Mine doesn't work either, I know its a wheel speed sensor, but too lazy to fix it. Meh.
4B) Maybe do a coolant pressure system test and see if it holds pressure?
4C) Depends, and probably leaning towards no.
4D) Budget at least 2k for a higher revving head. New rockers may prolly be okay for awhile at 7k, but I wouldn't push my luck. Also I'd wonder about the valve springs and their age at that point.
4E) MarkD chip is definitely worth it, but in your case for a winter car, I'd say no, unless you want a higher redline
6) iXs go in the battery tray area on the passenger side, behind the shock tower.
8) I would guess they would fit... Maybe Greg may have more of an idea.
9) Ya its got a CEL.
10) Not sure what trim you are referring to. Sorry man.
11) Some cars don't have pop-out windows. Mines ghey and doesn't either.
12) For 150$, should be able to pick up a used hub and wheel setup.
13) You want to remove the ashtray? Nothing that I know of to replace it.
14) Remote start? oooo... baller. Talk to Jays electronics guy.
15) No ideas, I would be too lazy to mess with it, just get another belt assembly from a parts car. Easy to change.
Greg has a washer fluid cannister from his parts car kickin' around. Give him a shout.