Granted I'm not quite 50 yet, but stoneskin on the tank seems pointless so far. It goes down instantly as soon as he pulls anyway. I usually use it on myself and the DPS so that nobody dies before I can do anything about it if they get agro.
For any newbie DPS or healers who might be reading this, always run toward the tank, not away. That goes for tanks too. I had a wipe today because the tank ran around a corner right before a Cure 2 went off.
