I recently played a Healer, and the party desperately needed one. The following feats I found helped a lot:
Spontaneous Healing (??) allows the dropping and casting of spells (limited number of times but enough). I think it was in Book of Exalted deeds (??)
Augment Healing in Complete Divine. With the Charisma bonus the healer had this (although small) modification added up.
The Healers Revivify spell was worth its weight in gold. A Raise Dead with no penalties except for -1 HP.
The other Healer spell that heals as you are struck (via Swift Action) saved a couple of PCs beause of the healer's high average healing.
I had toyed with the idea of adding the Feat that heals all targets of a spell found in Races of the Wild I think. This would increase the healing even more.
I had a surge of munchkin desire when I tried out Sudden Maximise. I might not make that choice again, however it was pretty good especially with a Mass Cure Light Wounds.
The fact the healer doesn't draw AOO while healing allows her to stand right next to warriors/fighters and heal, using the Swift Action spell on herself to stay alive.
The unicorn was a pain in the rear, and as a DM I would allow it to be changed based on player desire to something of equivalent nature. Every time I summoned it I had to "hide" the fact I was doing it because everyone would think it was out of the ordinary and then I'd be targetted etc.
As for healing at a distance there used to be a feat that allowed this in Tome and Blood or Defenders of the Faith I believe, giving a range of 30' for a touch spell, however I don't know if it has been reprinted. Now that would be fantastic.
I know the Hierophant can do this as a Special Ability choice.
I'm curious as to how a Cleric can do it at range as implied by previous statements.