Chose then your two classes very thoroughly.
Is there a class that is overpowered? (typical question...)

I have read something interesting about the classes of the game, based on the experience of a previous Radiant Arcana player who was telling exactly which class was better than the other. Nevertheless I think it's not something to speak of, as we want variation in classes. Make a class combo that works for you!

Who is going to be the tanking class?

The Knight is the tank of RoM.

What about the warrior then?

The warrior is going to be the melee damage dealer for the most part.

Will there be pets for some classes or for everyone?

You'll be able to have a pet (now it seems that there are no differences between the pets, one for everyone, nothing special for rangers or anything) by collecting some special cards, which tell you some specifications about a creature, and then you'll be able to take it as a pet (sounds like Pokemon). This bit of information is still unclear, however.

Will there be the possibility to own houses in the game?

You'll be able to own a house and to customize it. Your guild will also be able to own a guild house. Every player will have a house that you'll be able to personalize with decorative furniture, treasure chests, mannequins, crafting tools, housekeepers, bonus experience, and more. Every other player will be able to visit your house, and it will encourage social interactions and there will be a popularity ranking system.

The fact of owning a house won't take place in the real world of the game, and you won't be able to see the houses of the different players. You'll have to talk to a NPC to be teleported in your house, same thing to go out of it. By the way, each new player will be able to own a house from the very beginning of the game.

You can dl a video by maltaner 87 here about housing.

Will there be some special abilities like jobs?

Yes, like in other MMOs, you'll be able to choose various jobs. Some include gathering professions, where you probably gather raw materials, and others include manufacturing professions, where you create items.

Example:

*Gathering --> Mining, Herbalist, Lumberjacking...

*Production --> Alchemist, Blacksmith, Armouror, Botanist, Carpenter, Fisher Cook, Tailor...

*Dismantle