roam actions are used to ensure bots will patrol over to the node closest to a roam action. When the one action is set as a roam action for both teams then it can ensure that that area will be fought over. But roam actions do have other uses. I recommend at least 2 roams be active in waypoints at any time (in addition to any camp actions). Every class of bot needs an available action or it will stay where it is and complain about goals
Most actions that are objectives must be associated with the related map entity. The action_ent number identifies which map entity (existing in the bsp file or create-d in the map script) the action will listen to. For example; a construct command post action (22) must be set to the entity of the trigger_objective_info of the command post. That way the build final and death events of the command post are listened to by the bots and the aiscript. The console command /viewent (view nearest entity in fritzbot menu) is the easiest way to find the ent number to use. But beware the wrong number may crash ET when the bots join, so save often