Get I buy my discount ticket at the park I'm a teacher, if so what do I need?

Yes, look for the discount ticket lines (far right?) once you pass through security

I saw a guest service just past security anf there was a sign for discounts for teachers, military, etc. I think you just need a school ID.

Yes once you enter to the right , there will be three line enter the one you need go to for your discount

Yes you need proof to get them.

Yes, it is a Guest Service office next to the security point.