Yeah, although Prey will SMS me if that happens. What I can do about it, I'm not sure....
Still I can track the mobile using samsung dive. it'll tell me where it is. I can also remotely disable the handset, make it ring, inspect call logs and wipe data using this.
Oh, and as far as the usage app is concerned, I've found a good 'un. If anyone else is interested, Onavo Count is great. You can set a data cap on it and it tells you when you're near your limit.