A:AnswerAn unlocked phone means that the phone will work with any major carrier. This includes but is not limited to T-Mobile, Verizon, AT&T and Sprint.
A:AnswerYes. Buy the unlocked one. If you have a sim card in your current phone, just take the sim card out of your current phone and put it in this phone and it'll activate to your carrier.
A:AnswerHi,
Activate today means you have to upgrade an existing line or add a new line with your carrier and activate the line which would cost $45 to activate.
Activate Later means you will just get an unlocked piece and you can put any SIM card later to activate the phone and use it.
It doesn't matter which country you are in, if you are buying in your country then BestBuy should be able to upgrade your phone.