I am taking my priest to Molten Core this weekend and I would like to gather a little bit of understanding about the healing rolls and healing strategies that work best.

I am disc/holy, have 3600 life/6800 mana buffed.
I have 30/5 mana regen, and >150 to healing spells.
I use nightfin soup for boss fights for the 10/5 mana regen.

Any advice will be most appreciated.

Who are you going to MC with? A good leader should tell you your role in the fights as you encounter them.

Uh, a few no-brainer tips:
1) As a Horde priest, the one thing you can do that absolutely no one else in the raid can is dispel. Against mobs with nasty magic debuffs (Firelords, Lucifron, Baron Geddon, Firewalkers, Sulfuron) this is crucial.
2) Make sure you have everyone on RaidAssist (and uh, make sure your raid uses RaidAssist).
3) Learn to assist heal. Target the mob that's being killed and hit your assist key (F by default) to acquire its target. Usually that should be the MT, but mobs have secondary targetted abilities and many are tricky to hold aggro on. If you see, say, a Molten Giant turn away from the tank and start heading towards someone, you need to assist the Giant, find out what it's planning on pounding, and start casting that heal ASAP. If you wait until the Giant actually reaches the overnuking mage, he'll likely be dead before your heal is done.

I am going with Keen Formation + Quaratine, I use raid assist, I hope they do as well.

I don't belong to a guild atm, I think I am adopting the philosphy "I won't belong to a club that would have me."

Assist Healing - Some where I missed this in the manual, that is brilliant, I will have to do a couple of raids tonight to get the hang of it.

If a <moltenbadass> is dogging the over nuking mage; Shield + flash heal?
Spam flash heal until tank grabs control of <moltenbadass>?

On the dispeling debuffs, I am there already, it has been my experiance that
dispelling in a timely fashion is 5-6 time more efficient than a heal.

Thanks for the tips, any more information would be equaly appreciated.

The "best" healing strategy is the one the leader of your raid leader wants you to use.

Decursive or a similar mod will likely prove helpful depending on what roll you are assigned to fill. http://www.curse-gaming.com/mod.php?addid=643

Show up with lots of candles and full repaired.

Attunement to the Core <- Do that quest.

Well we got lucifron, on the first attemp to 3%, the a hunter added the imps in the adjacent room. Second attempt smooth sailing. Magmadar was a different story,
never go this guy to less than 50% in 3 attempts. We had only one tranquilizing shot and this was likelya big part of the problem.

While the leader provided some simple information, like "Ok we need to keep the dispells and decurses coming" It was never made clear as to while classes/rolls took the highest priority for dispells.

I gave the MT a two stacks of restorative elixers so he was golden for the luci fight.

Well trying it again tonight I hope that we do better on Mag:)

BTW gurgthok I have been practicing the assist healing, what a difference that makes, that one skill alone took my healing to the next level. That makes instances like DM and BRS, loads let work :)

The real question question is weather the hunter who agroed the imps is the same one you gave the t shot too.

I dont believe that is the case, though I really was not paying attention to that sort of thing, I was the odd man out here, the other healers had worked together before, so they were not comunicating much, I was trying to get some input from them. However I think the general excitement of the moment superceded discussion.

P.S. They had a MOD it was not working as intended. I am guess it was set up incorrectly.