perhaps off topic : UK lad looking for advice/info for working in USA AfterEffects/compositing work

This is something I have started to read into recently but I thought I would ask here in one of my favourite communities. My question is do many posthouses take on anyone from abroad? If I wanted to work in USA for some amount of time like I am now in London as a freelancer would this be possible (I have UK passport)How about if I aquired a fultime job? Im guessing a work visa is required of some sort. For our area of work is this a hard thing to aquire do you know. If I worked in a london company that had sister companies out in the states would the make a transistion easier (and be working full time)? Has anyone worked at a company that has employed people from London/UK? Im guessing there is quite alot involved paperwork wise if it is possible to be allowed into the country to work in this industry.

If Anyone has any experiences or information on this I would love to hear from you. I was initially thinking of GA state... Should I be looking towards other states to find work or increase my chances?
Many Thanks for taking the time to read this.
Regards
Chris