Want to play on European Server

Hello I am an American who lives on the mainland however I've also lived in the uk for many years. I still have many friends over there and would like to play with them. Now I've heard there is no transfer from European to American servers, so I would like to buy a European copy but I have a few noob questions to ask
1. Would I be able to dl a free trial and then upgrade later?
2. Will a european copy work on my computer?
3. Would I be able to pay for it with US dollars?
4. Would the latency be so bad that it would ruin my gaming experience?

Any assistance anybody give me on this matter would be greatly appreciated.