Here are some web sites you should see:
http://www.southafrica.net/heritage/heritage_routes/
mitchells_plain.cfm http://www.dplg.gov.za/html/progs/urpNodes/
MitchellsProfile.htm
http://www.faranani.org.za/capeflats/tships.htm http://www.socdev.gov.za/Statements/2003/August/
kaya1.htm
Your son has the chance to experience a life none of us can imagine. Thousands of people living in a variety of housing - some in very nice homes, some in not-so-nice-homes, some in shacks. This is an area populated predominantly by mixed-race South Africans described as Coloureds - Islam is the main religion, but that is nothing to fear, despite the drumbeat of warnings about Muslims. He should be cautious about his movements, displaying his funds and possessions. But he is essentially safe, if he is cautious. And he will meet some wonderful hard-working South Africans.
He will be very close to the water - False Bay. The nearest community outside Mitchell's Plain would be Muizenburg.. The basically all-black township of Khayalitsha is adjacent to Mitchell's Plain, and much less secure for an outsider. His hosts will make that clear.