Int = Spellpower
Spirit = Mana Regen
Crit = when you hit, you can hit bigger. More crit, more big hits (works on heals AND some DoTs as well)
Haste = how fast you cast
Mastery = depends on class/spec (and I have NO clue what priest masteries look like)
Hit = you need 17% hit in order to NOT miss a raid boss (only matters if you are tank or dps)
I don't know specific rating caps at the moment. Not sure the geeky math is in. The preliminary numbers are starting to roll in, but people are still testing to fine tune what they want.
Haste: Soft cap (whatever the number is) reduces the cast time. One thing to know is that you can not get the GCD to less than a second. 0.8 second Chaos Bolts are nice (DestroLock, I know) but kinda dumb, when I have to wait 0.2 sec to toss another Incinerate....
Do you need info on other caps and how they affect you? If so, the more specific the question, the easier it is to answer. Reaching into dirty water sometimes get you cut, and murky questions are like murky water.