As for being able to abort an already-started cutscene, there's no handy way. If a Duty Finder queue starts, commencing the duty will generally abort the cutscene so you can start it over again. I imagine this would not work for cutscenes that are triggered immediately after the completion of a quest, though. You can, however, just leave the game running with the dialogue waiting for you to click to advance. You should not be automatically logged out when you are viewing a cutscene.