Can unlocked phones receive regular updates and such. And lets say I get an unlocked Lumia 920 phone from At&t and take it to my carrier (MetroPCS) to activate it, will it work?
How your phone checks for updates is by the rom that's installed, so if you have a factory unlocked phone, it'll usually be first, then carrier phones after they test / change the rom if need be. So if you get a phone that was unlocked by the carrier, you'll still have to wait on the carrier to approve the update.
As I said over in your other thread... Look for an unlocked T-Mo branded Lumia 925. More compatible with Metro PCS service... It will update when T-Mo 925 gets the update no matter which SIM is in it.