To be honest, at his worst he looks like Mia (Arabian) does normally:
That is a pretty normal way for a lot of horses to move. If you want a significant amount of collection, then the dressage training scale can show you the steps it takes to train a horse for it. I don't because it doesn't matter to me. If it matters to you, I'd suggest getting some good books on dressage. You could also probably get some good ideas both for training and books by asking on the HF dressage sub-forum. Good luck!