1. You will still need a BlackBerry data plan from T-Mobile. Do you have that? Call to make sure your plan includes BlackBerry specifically.
2. WiFi will work on devices not sold by T-Mobile, but not WiFi calling. You may, however, attempt to follow these instructions to get UMA working:Get Your Unlocked 9800 Torch Working on TMobile with Browser, UMA and DM Tethering