Metro PCS legacy BBs

Does anyone know if an unlocked GSM BB will work on Metro now that it offers GSM? Thanks.

And is one required to pay an additional $10 a month to get BlackBerry features on Tmobile?!

May someone please explain to me how legacy BBs work?

Does the $30 Tmobile plan work with Internet, email, BBM, etc. and everything the plan offers in minutes, etc.? Or no?

Help please? :/

Anyone? :)