Getting Your number one choice has nothing to do with where you graduated from ( unless you graduate from USA medical schools if you want to do residency in USA)
it all depends on how good you do ( scores in USMLE 1,2 and 3)the last one (step 3 is necessery for the visa in USA
If you are not a US landed immigrant(green card holder ) or US citizen then the problems in chooseing you speciality is alittle bit harder than if you were.
any how you dont have to worry about the for now.
getting a family practice residency which is kinda equal to G.P in our world ( it doesnt exist here any more in North America) is very easy if you have very goood scores and if you do some rotation in US hospital( electives) and even if you dont it still donest matter .
the Letters of recomendations is very important too to get you good residency or good impression in the program you are applying to.
so many ppl i know ( international graduate got even Surgery res.)
any how Radiology,Dermatology,orthopedics surgery and i Guess now psychiatry is very hard to get into for international students but other than i dont think you will have any problems with ( esp. Internal medicine and Family practice ).
For me I am not in USa ,I am in Canada and its way harder here to get into goos speciality if you are not a Canadian citizen or didnt do your schooling here.
Uk on the otehr hand is much easier although you still have to pass their exams(PLAB) and then it takes a bit longer for residency traning than in North America.
Gook luck to you in your schooling and wish you the best
Regards
Amer