That's what I thought! But I didn't want to say that, fearing I'd be wrong! THought it was pretty safe to wait for you to reply.
Well the one loud click is normal. Mine does it and every Mercedes I've ever been in does it. Just for a peice of security though, and to protect the transmission, you should put on the parking brake too (if the car gets hit, like yours did, the trans could be damamged...I think).
Anywya, thanks for clarifying.