Divine Aura keeps any spell (or song) from hitting the cleric, this includes
Selo's.

I've always been told if you have a monk feign pulling, don't sing during
the pull. I have no evidence to support this practice as the only times I
group with a monk is on big raids (where you dont want to sing on the pull
anyway).

I good song to keep mobs off healers/enchanters is Melodic Binding.
Assuming you dont have a shaman slowing, this songs is great. Its slows and
ac-debuffs the Mob, doesn't break mez, and taunts them onto you. While we
aren't tanks, its hella better for the extra mobs to be beating on you then
the enchanter or cleric. OUr guild's main enchanter (who I am often in
communication with on guild raids) estimates this song moakes her about 25%
more effective at mezzing mobs. Mostly because she doesn't have to stun
before mezzing and if things go badly (multiple resists/lag usually) she is
in much less danger of dying (and to be honest if things go bad, I'd rather
just me dies then multiple deaths including the cleric, if just I die, as
soon as the fights over, rezz, mana song, and the loss is minimal). Also
from a cleric's perspective (my secondary is cleric), in a group without en
anchanter, when I drop my greater heal (lvl 30 group) I WILL agro at least
one mob on me. No biggie, stun, root, med. (Actually since we are the same
group every time we play, the wizard and I trust each other enough to root
each others mobs) BUT, if our bard is their, sining binding, I rarely get
an agro, and if I do, I just stand next to her for a pulse or two, then back
off. Much more effecient, and there nothing worse for a cleric than seeing
a teamate go down, while a mob is interupting your heals.

From both my perspectives, I say a good bard is an enchanters or cleric's
second best friend (a good puller is first)