Steveww, VelvetFoot
1. Discs 7-12 are accessed by pressing buttons #1-6 twice , for disc 7 you press button #1 twice, disc 8, press button #2 twice and so on.
2. There is no negative effect in the steering wheel buttons, they continue to be operational.
3. This is installed in a 2002 330i.
4. Because I wanted the OEM look in the trunk, I bought the BMW trunk carpeting for the CD Changer but not the installation kit with all the brackets. I measured the brackets and the changer will not fit. Maybe with some modifications can be possible but I did not want to keep spending money in something that I can fix in another way. Therefore I cut the OEM tray enough in the left side of the trunk to fit the changer behind the new trunk trim and still can use the same tray with the new trim without looking 'chopped'. If you are not interested in using the CD Changer trunk trim (and save $60.00) you can use the OEM left trunk tray and install the Changer there without trimming it.
Good Luck