Do hurricanes ever form below the equator? If yes, do they ever cross over to the north?
Yes ... especially in the Indian Ocean and the SW Pacific.
As an FYI, hurricanes south of the equator spin in the opposite direction (as do all storm systems in the Southern Hemisphere).
They can't cross the equator because of their spin (a result of the Coriolis effect) .. simply put, to cross the equator they would have to stop spinning and start spinning in the other direction. But if they stopped spinning, they would no longer be hurricanes. In fact, there CAN'T be a hurricane on the equator.