i have experience with all types of horses, and my advice for you is when he bites yell 'no' and spank him on the butt or on his belly with a crop, if he keeps doing it, you are not stern enough, elbow him in the chest right when he makes his move if you need to. this is not mean or crual and actually horses correct each other a lot worse, also he may be biting because people pet his noes, not all