Again you need to search on the DSP system and it's digital interface. This will define which MB-1500 to buy. I say this cos I'm not liking the extra display the Connects2 has, when the mediabridge can do it through the car's display. The only connects2 i'd get would be the phone only version or the CK3000EVO interface kit.

As to whether you have 40 or 17 pin, the only way to be sure is look in the boot at the tuner. It's under the carpet near the seats on the left I think.

If you have a BM54 (40 pin) you can add a simple aux in for about a tenner using one of the guides on here or E46 fanatics.