Hi I'm over in the US for 2 weeks and thinking of buying an iPad Mini on Friday. I have a few questions - There seems to be 3 carrier options - AT&T, Sprint and Verizon. Does that mean they come sim-locked or unlocked? - Is there any difference in the network technologies in the iPad for each network, or is the iPad the same for each? - Will they all work in the UK with UK networks - in particular the EE 4G network? Thanks!