Just do,
It doesn't matter to our governing body as long as your not exposed.
as long that your US citizen your oky..but ofcourse you need to recompense tax from the country that your going to stay next to.
about getting US passport..there's no style you could apply for it UNLESS your US citizen.
also if you have a green card and your staying more than a yr outside of the fused states..make sure you enjoy a legit excuse to do that and hire a lawyer newly to make sure that incorporated states of america won't think you ABANDON your green card.
virtuous luck
http://www.gurfinkel.com/