Technically, agoraphobia is fear of open spaces. So, school phobia could be one of the ways that this condition manifests itself. The person is afraid of venturing into an open space, the school, and is unable to proceed there.
Not necessarily. Agoraphobia is usually on a wider scale, to the point where someone doesn't want to leave their house for anything. Most agoraphobics are afraid of open, public places.
