The BMW parts catalog calls for Bosch WR9LS spark plugs. Also, if you go to the Bosch website they probably have 2-3 options for your car, though it's a little hard to navigate as I recollect. Here's the link to the Bosch website:
http://www.boschusa.com/home.asp
For the OBC problem, try to disconnect the battery for a few minutes so that it'll reset when you hook it back up. If your car has a radio code you'll need to know it in order to get the radio going again.