Heres a
link to another recent thread asking about seizures.
If you follow the link in my signature to the disABILITIES FAQs thread, post #3 has some helpful links - including some advice about autism and epilepsy.
Although it may seem like your world has totally changed, it wont be so strange or scary to you after a while. I am an RN and had seen several hundred seizures before my DD has her first one, but I was not much more prepared than any other parent. Its much different when it is your own child.
My DD has 2-5 seizures a month and she has had them on the plane and at WDW. Shes pretty noisy when she has a seizure, so people did notice, but it was not a real big thing. On the plane, we just kept her comfortable and then she slept. She cant walk, so has a wheelchair anyway, but if your child has a seizure and would need a wheelchair to get off the plane, you can ask the flight attendant to call ahead for one to meet you at the gate. Flight attendants are looked at like waiters and waitresses, but they are actually highly trained in first aid and emergency procedures.
At the parks, many of the attractions have wheelchairs very handy, so just let the CM know when you get out. There is a First Aid station in each park, open all the hours the park is open. If your child needs to rest after a seizure, they have cots where he can lie down in a cool, quiet environment.