When counting the months your son lives with you, you'll include temporary absences for things such as being away at school. As far as the support question, what you should be being asked in TT is, "Does your son provide more than half of his own support?" See the difference? You don't necessarily have to provide over 1/2 his support -- you can just answer than your SON doesn't provide over 1/2 his support -- a lot of his support may come from his stipend, but that wouldn't affect the way that you'd answer the question.
