I want to buy a US iphone 5?

I have found out that the US iphones are alot cheaper than the UKs. I have a friend going to the US next month and he said he would pick one up for me so i was wondering if i bought one would i be able to put my new Orange Sim Card into it and use it over here?

What can I do to keep my unlimited data plan on Verizon and upgrade to the iPhone 5?

Now I already know that I can buy one full price from Verizon for about $649 but I don't want to go that route, and I don't want to buy a subsidized iPhone 5 and end up losing my unlimited data plan.

Would I be able to just wait and buy a used iPhone 5 after it comes out and then have them activate the phone on my account? They wouldn't be able to take away my unlimited data would they?

Can i get an iphone without a data plan? How do i get the new sim card?

So i just bought an iphone 4 from someone at a good price. I know that my old sim card is too wide to fit into the iPhone 4 so what should i do? Do i need to buy it or can i get a free one from my account? Also, I don't have a data plan right now but do i need one? Can i get out of having a data plan? If so, how? What should i do?