I would imagine Dr. Paul has the same stance on gun control as the founding fathers, who thought citizens needed to be armed in order to be able to fight back against a tyrranical government. They recognized the trend for all governments to drift towards more and more power, control, and bureaucracy, and knew citizens might need to fight back one day, e.g. the Battle of Athens:
On the issue of guns in schools, I don't think repealling gun control laws on a federal level would affect the state, county and city laws preventing guns in certain places.
Its always seemed pretty simple to me. If people want tighter federal gun control, amend the constitution properly...