You will need your transcripts from your old High School. Your new school will need those as well as proof of residency for zoning. Contact your new high school to be sure.
You can transfer schools at any age under 18 with a parents approval.
Yes, although it depends with the type of high school and their system of education. There are high schools that transfer credits from English schools to the American schools.
No
by moving or changing addrees
you withdrawl and transfer to a different skool
18
Most schools require a C or higher to transfer credit
To move from one school to another in South Africa you need to submit a transfer card and latest school report.
In general, credits transfer from school to school (regardless of the state), so long as the schools are both accredited. You'll need to consult with the new school to see how to go about getting credits transferred.
No.
yes in some schools you can but some schools might reject you
I'm not familiar with MD law per se, but I think it very unlikely that the MD schools would approve/allow such a transfer.