You need to join up the BMW Club Racing email group located here:

http://www.bimmers.com/clubracing/index.html

There are tons of people who can help you out.

I can answer a few of your questions here:

Electronics: I don't know if BMW CCA Prepared rules allow you to chop up the wiring harness. You might want to check the rule book on that one.

Sunroof: You can remove the frame and motor so long as you then weld the a metal panel (either a custom piece or the original sunroof) into the opening.

Shocks: According to a post by the rules guys on the BMW list above, they have clarified the rules to allow DA shocks in Prepared until the next time for rules changes comes, at which point they plan to change the wording to make sure that DA shocks are legal in Prepared.

OBC: No effect whatsoever.