the light problem has a 99.9% chance of being a bad chip in your Light Control Module (LCM or LKM).
you have two options
1) replace the LCM with a new/used unit and have it coded (note: only someone with extensive BMW software tools can code a used LCM, and the dealer will NOT code a used unit).
2) replace the transistor chip that has gone bad - this involves sourcing the said chip, de-soldering it, then re-soldering the new chip.
the moisture is probably bad tail light seals. it could also be any number of drains - roof, sunroof, etc. etc.
the passenger side mirror dipping down is SUPPOSED to happen, so you can see the curb as you parallel park. don't like it? flip the mirror selector switch and it'll stop.
airbag light: have the car scanned with a BMW-specific software/hardware interface:
Peake (not the regular peake, but the one that does SRS)
check engine light: see airbag light - we can't help without you having the codes read.
Last edited by mattmartindrift; 03-16-2011 at 04:38 PM.