Hi, I read (somewhere) that you have a rattle in your sunroof - we have the same problem on our 155 V6! Our 155 has so many other rattles I don't know where to start. The main problem (apart from the sunroof) appears to be the doors. I might try the suggestion on the 147 forum which is to lock the doors. Let me know if you solve your rattle. Still it's a small price to pay ...
Rear pads are low or the rear caliper/s has seized (very common on 155, i've had 2 which have had this problem).
There should be a very good explaination of how to strip the rear brakes and fix this problem on this forum ...try search
and try alfa155.com.