1. When should a subtitle appear relative to the first frame of speech on the audio track? -It seems like on the same frame is too late, and that the ideal is somewhere around two frames before...

2. How long should the duration of a subtitle be? -Intuitively, the time should vary based on how long the spoken dialogue is. But what about one word bits of dialogue like "No!"?

Can someone point me to a standard set of guidelines for this sort of thing?