1: The unglyphed heal is calculated off the heal you receive. Keep your rage high to keep it fueled.
2: no clue, I haz no bonus. /sadbear

3: Looking at logs it looks like it was cut from half the heal you received to 1/4th. As for the health,
http://us.battle.net/wow/en/forum/topic/3657277546#6 is my only source, I'd wait to hear from someone with the bonus on it though.
4: it better not, I don't want to lug around a caster staff just to power my frenzied heals.
I totally missed 0, oops. Yeah, no clue on that either.