1. Up to three characters, so fittingly, one slot per class 2. No crystal clear word, but the assumption is no. 3. So far as we know, yes. 4. No official answer, speculation is this is a ability reserved for the hunters 2nd subclass 5. It is a timed buff that supposedly buffs both offensive and makes your regeneration health heal faster, we also seen clips that if the super is not spent when you die, you can activate it to instantly redrawn with the buff on.