There are no classes. When starting a new game, there are suggested stat distributions for warrior / survivor / mage types of play style, which you are free to accept, tweak or start with a custom distribution. The initial skills available depend on what skill class you choose for each character, but after that anyone can learn any skill after finding either a teacher or a book to open that skill type.
In the demo there is a button on the skill pane where you can show all skills, rather than just the available ones, though I don't think you can get a detailed description without having learnt a skill.
forum has a list of various interviews and preview for the game.