I have been using my US xbox for years here. I also bought a step/up down transformer. the one I have is 500 watts and its been working fine. I think newer xboxs even use less wattage. I bought the Kinect here in CH and it works fine with my Xbox. I plug it into the regular outlet here, although if you have a newer xbox I think it can be powered just by USB? not sure about that though as my xbox is ancient.
as long as you are connecting it via an hd source (hdmi, component) pal ntsc shouldnt matter.
I buy games when I am back in the states. Also a site that ships them here for a reasonble price is
http://www.planetaxel.com/
actually some games are region free and will work but its not always easy to find that out. its up to the publisher. most EA games are region locked and I have found rockstar games to be region free.
I also bought a PS3 here because those games are all region free and i can buy the games here or in the states...
as mentioned above games are much more expensive here...