Studying and Career in Medicine

Dear Friends,
As I come to know that , there are many obstructs to be a doctor in USA as an International student. So I am thinking for Studying In South America.
Which is one of the best University for Medical Student as an International ? How can an International Student get benefit in USA after become a Doctor ?
Can I get residency after become Dr in South America university degree ?

Please advise me.
Brijesh