Post some pictures!
This is it! Your car is prewired....
1. Cell phone. You do not want to use original phone, that was intended for this car. What you want to do, is to make sure you have a bluetooth capable cell phone, if you don't, then get one...
Unfortunately, BMW solution for bluetooth will not work on your car. You will need either got for EIS kit (www.eiskits.com
); wait for couple of months, while new kit called "Argos" will come out, or go for something like parrot, or sony-ericsoon HCB-30, or whatever. The first two will completely integrate your radio speakers, steering wheel control buttons, caller ID and voice dialing, EIS kit runs about US$630, I've been quoted US$430 for Argos. The others, I really never considered due to some function limitations, compatibility issues etc.
2. CD changer. You will need to buy new trunk liner and mounting bracket kit either from local dealer or on the net www.bavauto.com www.circlebmw.com
or anywhere else you trust. this will run you about $140-$160. CD changer, I would suggest to look into getting one that can play .MP3 files as well. Sources are the same and I would causiously add E-bay: there are a lot of screwy characters there and you can get even stolen or not working one, but you may save over 50% on changer....
The good thing is that your car is prewired! You do not have to run any cables, wires, cut harness or anything like that. Time needed to install CD changer is about 45 min. I did it in 1.5 hours: I wasn't in rush, I read through instructions many times, when they didn't make sense to me, and spend about 15 min. looking for the right harness in the trunk.
BT, they say takes an hour to install.
Good luck and contgrats on you BMW.