I had the 7100t at one time, before getting the 8700g. My big issue was not being able to see anything on the display at all when outdoors in daylight.
To you questions:
* I'm not a big user of bluetooth, except a gps puck. But see if Main Page - BlackBerryFAQ
helps you. Otherwise, I'll defer to others.
* I don't use use the tzones browser at all, except sometimes to look at my account. The blackberry browser (or opera mini) is the way to go. Do you have a blackberry data plan?
* "Was part of T-mobiles "blackberry" department . . ." -- I don't understand.
* I never had reception issues. That could be peculiar to tmobile in your location and not the 7105t. Or could be something with your individual handset.
* There is still no flash support in the blackberry browser. Of course we are all waiting to see what comes with the next generation blackberry.
On balance, my belief is you will be more than satisfied with the Curve. It will be a big change for the better.