LFG and Patch?

I looked for this information, but couldn't find it. I'm thinking of playing WotLK instead of BC but it depends on what patch the realm is.

The most important question I have is if there is Dungeon Finder. I remember that being implemented at the end and I absolutely hate that system.

Also, I would like to play a paladin but the patch matters because I liked it when they gave a buff to party members everytime they judged that returned mana. I think the mana shadow priests retruned was also changed to this system. But I can't remember if the buff was a set amount or based on the recipients mana pool or spirit.

Thank you :)