Well, they can live anything from 10-20 years in captivity - health problems can largely be avoided by maintaining correct humidity in the vivarium and not handling them too much.
None of my snakes were 'biters', and really were happy enough so long as they are handled only gently, not too often, and not surprised.
One of the most interesting aspects I found was in breeding the snakes, which was both fascinating and rewarding, and the local reptile stores were happy to take the babies off our hands. (Aw!) I would definitely recommend them as a pet for your son, who sounds like he would definitely benefit from the experience!