Question about T-Mobile Phones?

I got a little question. I have a phone currently that is Samsung Gravity Touch t669, and i am looking to buy a new phone like the HTC from the same Company T-Mobile. I guess my question is. Do all T-Mobile phone sims card fit??? Like if i put my sims card from T669 to HTC, would it fit? Would it contain the same phone #, so whenever someone called me it would go from the HTC? Can the HTC play games like Angry Birds, and Plants Vs Zombies? Can i still upgrade my plan even though my plan is with my parents, like pay with my own money for internet and texting? Thanks!!!