I agree with the others that the horse looks a little "up" and tense.
His form with his front end is good, but his hind end is loose and trailing.
Because of the lack of release, and the general tension, he is jumping very flat, even hollow; more like an equitation horse than a hunter.
I am not a big fan of jumping with draw reins, and I'm a little concerned that you want to do hunters but are schoolinog a horse in a figure 8 noseband and drawreins, neither of which are allowed in hunters.
An ideal hunter would hold a steady rhythym in the canter on a light passive contact all the way to the base of the fence, pat the ground as the rider softens contact in the take off stride, and drape itself over the fence in a symmetrical round arc, with knees up, even and square, head and neck stretched forward and his withers as the highest point on his body. That's not what's happening here.
I would agree with the half halting all the way to the fence on a jumper or event horse, but not on a hunter - the ideal is to set the pace and balance in your opening hunter circle and maintain it around course with minimal or no adjustments. If you nrrf yo half halt in the hunter ring, they need to be no more than a 4 on a scale of 1 - 10 and invisible to observers.
I like your position in the air VERY much. Good solid lower leg, correct base of support, right over the middle of the horse, flat back and eyes up. If you had a more generous release, it would a very pretty picture!
Of the set, the third photo is the best and the most hunter like.
If I where coaching you, for the next two months we'd working on getting him to stretch forward and down with his head and neck and use his back on the flat, and maintaining a relaxed, steady rhythm at the canter. I'd have you canter a lot of poles on the ground and courses of poles until he developed a "this is no big deal" attitude.
I would also build a lot of low grids and gymnastics and have you ride through them on absolutely loose reins 1.) so he would start using himself better and 2.) he learns to back himself off of the fences on his own. He's a horse I would like to set up tight distances in a grid and sort of kick him through on loose rein until he figures out life is easier if he shortens and balances up his canter by himself rather than burying himself to the base and jumping from way deep.
Good luck, and I would love to know how it goes. He seems to be a challenging project, but it looks like his heart is in the right place and that he wants to please