Time and experience or read the boards and practice or both. I prefer to find out stuff on my own and fill in the blanks by reading up on stuff or asking questions with my characters, that way not only do you get good but you develop your own unique play style.
Is the Apprentice at negative frames when he force breaks a grab? I can get his 2A to trade with Setsuka's 2A, both being i14. This makes me think its neutral, but a friend of mine told me he was at disadvantage after a force grab break.