First of all, thanks to dvaskelis for an outstanding reply, that's the most I've learned about T-Mobile and BlackBerry at one time.
To the original post, let me provide an example that may help. I currently have with my Curve 8900:
myFaves 1000 plan - $59.99
BlackBerry Unlimited - $19.99
1000 text messages - $9.99
For a total of $90 a month for unlimited blackberry data (#3) and unlimited GSM voice calls (#1) to my "fave 5". I can use any wifi access point (#4) I want and browse for free without touching the T-Mobile network, as pointed out in the previous post. However I do not currently have HotSpot access, which would allow me to connect to T-Mobile wifi access points, nor HotSpot@Home (#2), which would allow UMA calls at such access points.
Hope this helps.
I do remember hearing about some bundled plans in the works for unlimited BlackBerry + HotSpot + some text messages for like $34.99 a month, but I haven't seen anything concrete.