Welcome to the boards, Luisagos :)
PlaneShift is rather early in development, so not all features are there (and many are limited).
1. We have no classes, but a skill-based system. You choose what skills to train in any combination and number you may want.
2. Currently our NPC AI is taking baby steps - NPCs will walk towards their attackers, but that's about the extent of it :) We're trying to get them to run now. There are no boss NPCs at the moment, although you may see a King Ulbernaut (or its equivalent) surrounded by its lesser minions with time :]
3. The key point in PlaneShift is active roleplay - it is both encouraged and to a certain extent enforced in the game. As the number of things to do using game mechanics is still rather low, players form their own quests, stories, and adventures.
Magic is suffering a bit at the moment, but we're aware of the many issues surrounding it and the need for balancing, and Xordan is our magic guy on the team who will be working to fix it. You can take a look at a pretty thorough magic guide
here. The Guides and Tutorials section itself is a good place for potential players, so I would recommend some browsing whenever you have time.
Hope you enjoy your stay :)