Welcome to the dark side!!!!!! It's much more fun over here!!
I got taught to stay in 2 point until 5 stride out of the jump then sit light seat in 3 point, then land in 2 point and continue!
The most impotant parts are a) trust b) heels down c) adapting to the situation.
Sometimes with different jumps your horse will jump it differently. Obviously with drop down or jump up. I got taught to stand upright for a jump up and let the horse come to you and a drop down to lean back. In some case I would just let the reins slide through my hands and gather them after the drop. I know but that's just my style. I trust ozzie so I know that I can control him no matter what the length of my reins. (thanks to the campdrafter that taught me the one rein stop)
I don't think there's anything wrong with using what you learnt from hunters to mix it up with your position to find a sweet spot that works for you. (i think I know what hunters is)
There's no right or wrong, it's what works for you and your horse.
Off subject a little. I went and watched my friend ride her first event on her new horse, there was a man riding c grade (85cms) and he was between 70-80 years old. He was riding with very long stirrups. He approached the tent where the jump judges sit, the horse reared and carried on, he sat there like it didn't happen, then went around doing the nicest round i've seen, got a little lost, but got clear. He was an old stock riding that decided to go have some fun eventing...it was his first event :) he was the only person that would ever pass gear check in jeans!!! LOL
Anyways, good luck have fun!
Also, use your imagination on creating jumps to practice over to simulate cross country jumps!