Don't bother with the mind square/healing tree. Mind square is useless because you have to sit for it to kick in (which I'm sure not many people do while grinding).
A:The MOST IMPORTANT STUFF is all the heals, evil sound, sound of heart, and sound of spirit. Magic upgrade is pretty good too.
Water skills aren't necessary. The masteries are useful too, EXCEPT the expert. That one is a waste of points (Just put 1 so your elemental can take effect)
oh also, level 90 heal>recovery sound (heals faster more , heals you too, spammable)
B: Elemental flow isn't necessary at all unless you are a grindaholic and want to attempt to save pots. Even then I wouldn't recommend it until level 90 (when you are able to max it). It's more for soloing too.
I should finish my bard guide ._.
edit:Since you probably want this:
I think that's it...