Pets will not cause any experience penalties. A pet is completely loyal. You may summon multiple pets at once granted you have the power to do so. A follower is a permanent creature that is bound to you when it is at its lowest level. You may have multiple followers at once.
Followers are completely loyal.
There will races but no classes. Players are free to develop in the areas they choose. Certain races will be more adept at different types of skills based on their base stats. Stats play an absolutely crucial role in this game. Stats go up according to your base stats each time you level.