advice/help/questions..

[PACMAC]

so im gettint a 16gb next week and i have few questions..?

1.im a t-mobli user and my contract is going to expire soon like 3 months from now..can i use t-mobli for now then later if i want to be ATT can i restore it back to sing up with ATT?

2.what works on t-mobli? like youtube safari ect..

3.whats the best method as of now to unlock/jailbreak it..?

4.will camera support video any time or that has to be a hardware upgrade?

thanks