Re: Moving to the US
If you want to, you can but you dont have to.
My friend had a GC and she did all her studying in Pakistan, she did not have to take TOEFL for her Masters (I think she went to San Jose), infact she did not even take GRE. A cousin of mine (GC) had inquired and he did not have to.
TOEFL is a requirement for foreign students. A US citizen is not a foreign student, but inquire with the universities you plan on getting into.