If you have minimal MMO experience, I'd suggest the Pyromancer class. It's a very simple and straightforward class which will sit well with beginners in the game. But just because it's easy to start out with them, that doesn't mean that they're a weak class. I've seen some Pyromancers deal serious damage in PvP.

MMOsite: When players fight as a team, which class can take the major tank role?

That would most definitely be Shaolin class. The Shaolin have tons of health and are equipped with a multitude of buffs and taunts that allow them to be the perfect tanks.

MMOsite: And the DPS?

The DPS in the game is spread pretty well amongst all of the classes. Some classes lean towards a specific type of damage, but the end result is still the same. It really all just depends on how you like to fight, some people prefer melee, some prefer ranged and some prefer magic. Whatever you choose, you'll definitely be able to hold your own in combat.