Yeah, in boosting a group of 5, you need to rotate the character that sits out. What I did, was i got a mod that shows the percentage through that particular level. That way, I'd check and see which character was ahead of everyone else, and sit him out. The 62 warrior is your best bet.... but not being 70 will probably hurt you a bit. You'll be able to do SM, but not in the same amount of pulls, or as fast as any of us that have done it.

For pulling, just park your shammies at the entrance of Deadmines and pull the first 2 full rooms and run the warrior back to the entrance. As long as you're <100yrds from the characters, they'll get XP.