My mare did all of this. This is a combination of the horse feeling nervous and fearful of other horses, and not trusting you as the leader to deal with the other horses so he takes matters into his own hooves. First, go back to the ground. Start at square one and work your way up.
A big turning point for us is when I took her to a trail obstacle class once a month for a few months. It was very good for her because she had something else to focus on other than the other horses (it's also great for "spook-proofing" your horse). Riding the arena on the rail continuously is not making the horse think much, so his mind wanders to worrying about the other horses and he pays less attention to you. For this reason, give him things to do and don't repeat the same things over and over so he never knows what to expect. Ride a figure eight, canter a round, trot the cavaletti, practice switching diagonals across the arena, whoa, turn on the forehand, walk to canter transition, etc. Keep him moving, keep his mind working. After doing the trail class for a few months I went to the local arena's "open ride" night which is great for training horses. Basically it's the same thing as the warm up arena at shows. I followed the "keep his mind working" practice I mentioned before, and didn't leave her time to worry about the other horses. Anytime the ears started going back, I would pet her and talk to her reassuringly. However, if she attempted to bite or kick another horse, I would give her a solid smack with my dressage whip and drive her forward into trot or canter. Sometimes, all they need is a little reassurance. But if they attempt to "take matters into their own hooves", you must correct them immediately. When driving the horse forward to make him work, don't just do little circles. Circles don't do anything, and I won't say what it does for the horse but it certainly drives me crazy. The key is to keep him focused on you, keep his mind working. Don't become predictable with him, he should never know what to expect. Following this will keep his mind on YOU, not on the other horses. If all you do is circles every time he acts up, you become predictable, and it does not solve the problem.
For the show, it is your responsibility to put the red ribbon in and make it visible and noticeable. After that, if somebody gets kicked or bitten for being too close to your horse, it is no fault of yours. It is theirs for not paying attention (but you should pay close attention also of course).
Key ideas: keep his mind focused on you; take him out to other places and ride him around strange horses as much as possible; reassure when he becomes tense or nervous; any attempt at another horse must be reprimanded with a smack and driving him forward. I recommend carrying a dressage whip with you always. I find it much more effective than a crop or spurs, and if you just need to remind the horse, a flick is all that is needed from the dressage whip. You have to work harder with the crop. I don't use spurs anymore because I am aiming for the goal of being able to ride my horse without whips or spurs. Spurs do not create a horse that is light and responsive to the leg, they create a horse that is responsive to the spurs. On top of that, I don't trust myself jumping with spurs.