I guess I don't see anything be aware of--
Proprietary software is proprietary, not open source or inter-operable.
Don't see much advantage in the BlackBerry world for MMS. Sure its fun with camera phones and the like but on a BB?
Same as previous poster, enough calls to know I don't have account lockups. Maybe you are asking them to perform specific things on your account provisioning and that's causing the problem?
Unless the BIS email is your sole email account, then having it collect emails from (up to) 10 other accounts does not cause a storage space issue. Every plan I've ever known has a base storage amount and you pay for extra- nothing unusual with that.