1. Doable when dualboxing, and worth it since you're not going to be able to grind elites as fast as triple to five boxing groups.

3. Quest. Since there's only two characters when dualboxing, you split the experience points. Grinding is horribly slow, since there's only two of you of course. It's what made me lose interest at level 42.

4. Hunters have extreme DPS and two pets that can tank and be healed, two traps for CC and DPS and all that stuff. Mages have free water and food, hunters have zero downtime. Mages have portals and teleports, Hunters have nothing. Mages have better burst damage and can AE grind, hunters don't. Since exp earnings mean a lot - go with mages.