if it's your first team, i would suggest 5xelem shaman, or 1 paly tank+4 shaman, as it will be MUCH easier to set up compared to 5 different classes.

What's your goal? pvp? pve?
not sure why you'd want to level 7 toons.

one of the comp i like is Prot Tank / Holy Priest / Mage / Elem Shaman / Balance Druid.
I don't really like the (permanent) pet classes
That comp gives you all the main buffs, lots of off healers, an off tank if needed, brez, pop, lots of cc, a stealth class if needed to trigger whatever,
it also give you a reasonably good distribution of gear, as only the priest and mage fight for cloth, and in the end one will get the healy stuff, and the other the dps stuff (although they are often interchangeable i guess).

my2c