Any dps/healer that pulls mobs before tank deserves to be devoured by the mob lol. I absolutely will not pick up anything that's not pulled by me as the tank. As for small/big pulls it depends on the tank, some tanks like to test big pull first to see how the healer heals or small pull to see how they handle that; some tanks ask the healer first which is fine, there's no right/way to decide on pulls. The rule I use is that if it's a non-leveling dungeon I'll do big pulls, if it's a leveling dungeon I'll do small pulls, it's a good rule in my opinion.