Stars help you level up. The more stars you get the faster you level up. In combat classes you can add the stars to a skill. This will 'level up' the skill and give it more 'power'. In order to do...
You could get rock star clothes from TCG Booster Packs. The Rocker Pants, however you get from Physical Booster Packs and I'm not quite sure if they still sell them. But there's an air-guitar emote...