answer to pull question:
not much, unless you are sending him out to sap one of two mobs and pull the other or he can do crazy damage with ambush and wants to start that way...but short of using sap there isn't anything he can do that a hunter,druid, mage or anyone else with 35+ yard range can do (I play a rogue and a druid)
answer to rogue group question:
most people have no idea what a rogue is capable of, rogue in a normal group is severly limited, rogue/druid combo is insanely effective, rogue with a bunch of caster is likewise insanely effective, group of all rogues is nuts, rogue in normal group hmmm bring mage instead. Net net, don't expect to get many invites for normal groups, learn to solo, find friends you work well with and go from there
- btw the easiest way for a rogue to make perm friends. You can pull an aggro 100% of the time off a caster with a good backstab (if you use swords your out of luck) druids/priest/mages/warlocks will definitely remember you when you're the one constantly pulling aggros off them and dragging them back to tank types...