Short answer is, it depends on what Arena you are talking about. In the Special Events, and Training arena, there are rules posted in the arena message when you log in, since both are structured enviroments.
In the Main Arena, not so much, but if you happen to accidently do something 'wrong', either the game is designed to let you know, or you will get feedback from other players.
Since AH is an air combat, and war sim, there are many 'rules' for how to accomplish things in the game. But as far as player conduct in the Main Arena, don't do anything you wouldn't normally do in mixed company, and you'll get along just fine.