Some permanent changes (voice, hair growth, male pattern baldness, downstairs growth) would remain, but fat would be distributed back into a female pattern, that once a month thing would return (if everything was still intact), lipid levels would likely return to pre-T levels, and sex drive would most likely decrease.
I doubt any surgeon would perform a meta or phallo on someone under 18. The SOC suggests that a person be the legal age of majority "in the patient's nation." While these are just guidelines, I don't think most surgeons are going to look past that one, with or without parental consent.