Unfortunately this is the consequence of having such an open platform of a game. Arma has always been an extremely modifiable game, which is a major part of its success, this also leads to people being able to hack in extreme ways very easily. Of course the hacking has been made a hell of a lot worse with dayz bringing so much popularity to the franchise.

The best thing you can do is join an active Arma community in your area and use their private servers, your also going to get the most out of the game play doing this.

yeah all over the internet arma 2 scrips have been imported to arma 3 and are gone free worldwide.

some of these are caused by people with the Dev bundle of arma 3 bought from steam joining a server. they are working to fix it now

Anti-cheat is being worked on. Reporting the general issue of cheating is not necessary.