Pally buffs:
Pallies have about 10 different 5 minute buffs - "blessings"
+25 mana / 5 sec - wisdom
-30% threat - salvation
+10% all stats - kings
+ attack power - might
and so on, freedom, consecration, loads!
each pally can only cast 1 blessing on a given person.
So in a 5 man party, the healers + mage might get salvation, tanks get might, etc.
If you have 2 pallies, each pally can cast 1 blessing on you, so mages might get kings and salvation, etc
So in a 40 man raid, before a boss fight, you'll get ALL the pally buffs at once, each pally casting 1 blessing on the whole raid. It takes them a few minutes at the start to sort out the buffs (pally 1 does salvation, pally 2 does wisdom, pally 3 does....)
and then that pally keeps the buff on you.
Cos they are 5 minute buffs, generally they only keep the buffs on the healers during the battles. I.e. it takes 2 minutes just to cast em on 40 people, so by the time the pull comes in, you only get about 3-4 mins "fully buffed".
Hope that answers the earlier questions.
On an aside, Blessing of Salvation does totally own in raids. The reason being that if EVERYONE except the tanks have BoS on them, effectively the tank is producing 30% more threat than anyone else. With this in effect, a few sunders, and few revenge, and the mobs stick to the tanks a great deal. The rogues in our PvE guild really notice that when fighting the molten giants, which pound them in 2 hits at times, having BoS means they simply never get the aggro.
On aggro management, in long boss fights, druids can catform-cower, rogues can vanish and hunters can feign death midway through, and carry on casting / killing
Braidwood.
