It is not a phone so you dont need to unlock the tablet, i bought two of this items and work very good, the only thing that you have to be concious is that memory could not be enough for you. You can buy a card to get more memory on the device
It works fine in the us, in the Midwest where I live. I assume it is covered by US warranty, as I went to the Samsung website and found the model, and then registered it to my address for warranty registration. It works well.