Actually, I did order another mounting cable. I wish I didn't have to, though. It would've been better if they had designed it to be removable in the first place.
As for the bag, I concur that it's completely waterproof. The bag itself is really nice. The only design flaw is that the lock secures the bag to the mount, but doesn't secure the contents. So, while the bag itself won't be stolen, everything inside can be. :-/