As was mentioned, race horses are trained to lean. I wouldn't necessarily go to a harder bit. Lots of changes of direction, circles, serpentines will begin to bring him back a little. Do your half halts if needed on a circle or bend; he won't be able to lean quite.
This. Very normal for an ex-racehorse whether he raced or not. He just needs to be educated not bitted up.
Here are my thoughts, based on experience. It can take time to get them to move into the bit, versus them trying to get above or below or behind it. If you and your trainer can do dressage with him that would be great. A lot of people just leave their mouths alone, but I think OTTBs can really benefit from learning how to actually take contact and push into it usefully, and this is a perfect time to teach him this. The leaning does need to be addressed, but it is sort of normal because he probably lacks the strength to carry himself. So good dressage work to build his topline, from poll to tail, will help him develop that strength and learn to want to take contact. The difference between a horse who is leaning on the bit and one who is moving confidently into the bridle, from back to front, is night and day, and is an important step toward proper jumping.
Bitting up is useful in a lot of circumstances, but for flatwork it can get in the way of developing the good communication that will (hopefully) carry over to jumping. My last two TBs, both jumpers, went in loose ring French links, and I actually moved my older guy back down to a nathe because he doesn't like metal bits. Every young OTTB I know right now goes in a French link, actually. So, yeah- I would see if dressage helps (with a really good trainer if your own doesn't do dressage), and go from there.
You can take a line and say it isn't straight- but that won't change its shape. Jets to Brazil
To Rel6, I agree with your leg comment. He responds well to leg aids for the most part. His biggest issue with leg is when he is tired or feels he is done. He then throws his head up, tucks his head up and under the bit and gets rushy again. This is where additional leg and circles have become my friend. I do feel that balance also plays a big part here. He seems much more balanced at the canter than the trot which kind of confuses me. My goal is to try and make my life and my horses's life as uncomplicated as possible since his age lends its own set of challenges (attention span, growth, balance, etc.) Lots of great feeback here and I really appreciate all the good ideas. Cant wait to put them into play
Very good point here foursocks. I would love to get some dressage lessons and actually already have a plan in place for that. I feel like my horse is choosing to ignore me at this point when I ask him to slow it down. I dont think it is as much of a balance issue as it is an attitude thing. He wants to rush through and do it all on his own. Confident little bugger he is! And I do plan on jumping him in the future and would love nothing more than to have him carrying himself into the bridle like you said. He would definitely be most happy there. Now if only I could explain it to him that simply! Lol!