WOW! I think your horse is Exactly like my pony xD
What I did to fix his pulling on the lead was just backing. I would lead him, if he pulled I'd stop and (without moving my body, still standing next to him) I'd give sharp jerks on the lead rope until he backed up (starting soft and building) and I'd stop when his nose was a bit behind my elbow. I did this several times until he realized he needs to always be at my elbow. It didn't take him long.
Now!!!! You said my magic words - clicker training. And you BET it helped my pony and his terribly over-active brain!! My pony came to our rescue several years ago - he was a beloved children's pet pony - he would let himself out of his stall every morning to have coco-puffs with the kids. He was smart and sweet and he ruled his roost. He came to our rescue and we quickly found a home for him. At his new home his job was to pony ride the new owners 11 grand kids on rare occasions. He lived in a paddock with 3 other very large geldings who bickered all the time - he was 3rd out of 4 in heirachy - he could beat up the submissive old guy. But needless to say his size difference left him some serious injuries. These went unnoticed by his family who thought all horses could live happily together so long as there was enough food and candy for everyone. He became pushy and aggressive - never being allowed to sleep and having tack put on his broken rib lead to a very violent little pony. He continually bit his pony-ride leaders, to which they would untack and put him away. No one was allowed to discipline his rudeness and no one tried to find out why he suddenly turned 'bad'. One day he finally had enough, he was being ground driven by a professional trainer - who was also giving a riding lesson in the same round pen? The pony spun around and attacked her, all four feet and teeth. They promptly loaded him on a trailer and dropped him back at our rescue.
At this point I was getting ready to move and my mare needed a companion at our new home. He would not be able to be rehomed - he's now a 'liability'. So I took him with me. He was a TERROR. His injuries healed and he slept a lot
. But he would pull (or even break loose) on the lead, he bit constantly, he was just a general little snot.
I had decided to just let him 'live out his life' and not bother, he was my mare's companion and that's all - so I made him be mindful for being turned in and out, but otherwise left him unbothered.
Then I learned about Clicker Training on here. Being a biter and a mugger I ignored it at first. Then I thought 'well he can't get worse
for it' So I looked it up and found that CT actually fixes
those mugging-type horses.
Well I tried it. My pony is more polite than I've ever seen him, he no longer invades my space -ever. He does all sorts of silly tricks, he backs up, gives hugs, touches targets, kicks a football (I wanted him to fetch but he preferred kicking :P) and now he's learning unmounted agility. I also just got the OK from my vet that he's healed enough for driving, so I'm working on teaching him to drive now. Let me tell you!!! With his little mind and body working now, he is the best little pony I could have ever asked for!
Personally I use a mix of Traditional and Clicker training (mix of pressure+release+treat - mix of positive+negative reinforcement)
If you're interested in clicker training and want to learn the facts about it all, the psychology behind it and methods on how to do it effectively and keeping the horse respectful and behaving the entire time read this thread: Clicker Training: Challenge Accepted
There's some fantastic information in there!!