Achievements och tittles i MOP

Titles that wont be account wide are the ones such as the old school pvp titles, hand of a'dal etc. They give you a FoS for earning them, and you will also have this FoS over all your toons.
So in short:
If the achievement rewards a title, ALL your toons will have it, as long as they are level appropiate.
If the title rewards an achievement, all your toons will get the achievement, but not the title.