Don't forget about Holy Radiance, it's your big AoE heal. Pop that with your CD's during heavy AoE damage. Your group will go from 50% to full health in no time.

If you have a melee heavy group, Light of Dawn (Holy Power AoE) is a great source of heals - all the heals contribute to Beacon of Light heals on your tank so you get some good bang for your buck. If you have a caster heavy team, Word of Glory is a nice mana free heal.

As far as crit goes, my experiences with it have been lackluster. I found it didn't help much (sorry I don't have data). I reforged it all to haste, mastery and spirit (if a piece didn't already have spirit on it). Healing has been smoother since then. In 4.2 with 200% crit heals, crit will be much more useful.