Poor kid! I'm exhausted just reading your description. I'm no Kriston, but here are some links related to Myers-Briggs personality testing:
http://en.wikipedia.org/wiki/Myers-Briggs_Type_Indicatorfree m-b online test
http://www.humanmetrics.com/cgi-win/JTypes2.aspAlso, if you do decide to homeschool, I'm sure Kriston or other homeschooler parents will tell you there are lots of social outlets for homeschooled kids too. (And some districts will allow partial homeschooling, where your child can go to school for the nonacademic stuff and sports etc, and get homeschooled for academics.)
Even extraverts need some recharging. I'm an ENTP, with a preschooler at home. I need some alone time at the end of the day, even though I do get recharged for the most part around other people.
It might also be helpful to talk to your son about making sure his own needs are met, including relaxation and fun time, before he pours himself into to many activities helping others. Also, maybe a conference with the teachers to discover if there's a way of assigning group efforts so that the lion's share is not done by your DS.
