Sorry, I am not much of a boosting person. I wanted to experience it as it was going to happen later (when you are bigger the higher level char isn't clearing as much and you have to transition to a different playstyle). So I made a temp char to fill in until the group gets bigger to match my main (yeah, mine is only 40, so it is closer). You might just make a 5th shammy so you can see how things work instead of just getting run through places. You will probably learn tactics that will help out later.

I use a setup that lets all my chars tank/heal/melee/cast. I rely on sharing aggro and using generous use of totems. 1 is more elemental/resto. 2 are melee/resto. 2 are resto/barely elemental. I use 3 stoneclaws, stoneskin and strength, searing, 4 healing, 1 mana, 1 agility, 4 grounding. Then I lightning pull (usually 2 casts) and kill 1 mob, while other are busy with stoneclaws. It works pretty well. Even if the mobs get done with the stoneclaws, they don't focus on one guy and the healing totems almost make it so I don't have to heal. It seems work for me.

I would worry about playstyle more than levels. Levels you can get, if you stink at playing, levels probably won't save you. (I don't mean that in an insult way, just as to learn to control 5 chars takes practice.)