1) Wizards have a very high damage 76+, and most of the players here on the server prefer AOE, but it is very relative, in the course of the game, you will see that there is everything.
2) As I said, most players prefer AOE, but there are also several single target groups in TOI / LOA / SV, always relative.
3) Yes, I always say that it's worth just playing the class you like best, because of your commitment to the preferred class, consequently you will be a requested player, not by the class, but by your fingers.
4) Supply and demand.
I hope I've helped a bit.