Training can begin at 15 years and a Student Pilot Licence can be issued
No Upper age Restriction, but a valid medical is required.
Yes, English proficiency is a requirement by law, minimum is a Level 4.
Yes, that is possible. The only implications are that one would probably take a longer time to complete the course, and will exceed the minimum required hours to obtain a PPL due to infrequent flying and progress of skill. This will not affect training in a negative way, apart from cost implications, provided that one does not exceed maximum hours for certain phases of flight.
You can choose to pay the amount quoted in full or you can “pay as you fly”.
Yes, you may conduct training and obtain a South African PPL/CPL, provided that the appropriate study VISA has been obtained prior to training commencement.
Depending of the state of Authority, most countries will accredit the holder of a RSA PPL/CPL with experience gained. It might be to the jurisdiction of the concerned state, to validate such a license, or issue a home country license, provided that certain, or all, theory exams might have to be re-written; and is also subject to a skill test by a DFE for that state and type of license application.