hello vemel,
I will admit that i just started raiding heroics this week (10/13) as resto. My toon is called xmogpolice on area 52 and i'm in the process of switching over a lot of my gear. Feel free to look at some of my logs as I have some ranks (albeit low but considering my late start they aren't bad) so feel free to look at some and maybe give you a better understanding of where your healing is going to come from.
i heal with the same comp of healers as you do with a disc/spriest being our swing healer. i myself am behind the hpally and others in gear but manage to keep up. I recommend getting ~3900 haste (breakpoint + lag leeway) with AS and PE. Past that i go for crit until you hit the soft cap (healing surge 100% crit with tidal waves). Even on heroics you don't have many people who dip below 50% for very long and crit is useful at all health percentages (especially single target heals) and refunds mana. Overall your numbers are going to be lower than the holy pally due to the nature of the beast. Don't feel too bad as 5.4 will make this a lot better. However Nothing beats Shaman CDs when it comes to healing and we have a lot of them.
As for spell selection keep in mind the following things.
1. is healing rain going to heal a decent number of people for the duration or not? If it isn't don't really worry too much about using it.
2. Do i need to use the chaining glyph for this fight? How bad is your stacked damage and how much spreading will you have?
3. Is mana an issue or can i clip hst? Now this is usually a non issue but some fights go long and having that extra mana is a vast difference in regen.
4. Red, Yellow, or Green? I use these terms from my heal bot as thats the colors raiders are painted depending on how much health they have. Typically if they are red, use HS, yellow use GHW, and green use HW. However if you can/need to use Chain heal or Healing Rain do so before resorting to single target.
5. Is someone going to die? Almost every rule can be broken in order to keep someone from dying. In fact this is your sole purpose in the raid and don't get distracted by numbers if bringing you over that druid is the difference between a wipe and killing it.