Tank: Druid - My only option because I want to be able to shift to 5 long range DPS

So I need 3 DPS and a Healer from the following:
Shaman
Mage
Warlock
Hunter
Priest

- No duplicate class
- A composition that will have the most buffs
- Has the most DPS output
- Has the best heal multiboxing wise
- Easy and fun to play like my good old Paladin + 4 Shamans
- What talent tree also should I pick for each class

Thanks for your help