Auto-start options are in the event options when you double-click them. I believe it's called the Trigger Conditions or something, but it's located next to the event graphic and is usually set to "Action Key". This can be set to "Auto Run" if you want the hero to not be able to move while the event is occuring, or "Parallel Process" if you want the event to run while the hero can move.
As for NASU, the game is programmed through some very complicated event processes that are hard to replicate.