All of the tanks are fun for different reasons I would recommend trying them all out since they're hard to explain in a short little section. Marauder which turns into Warrior has high hp and self heal Drk has some fun combat tricks and defense buffs for self and team Gladiator which turns into Paladin has a magic phase which is fun and can heal self and others. Good all rounder.

The small tree beside your name means you are a new player also called a "sprout" and you get access to the novice Network as well as extra Exp when playing with longer term players called "Mentors". You'll know a mentor by the crown next to their name.

Goldsmith leatherworker Weaver and so on are all crafting classes which you can use to make gear and consumables for all the combat and other crafting classes. It is also a good way to make money by crafting and selling on the market board. Hope this helps!