I know that some places they only hire freelance and then you have to work up to perm unless they really need someone then. So in some regions you don't really have a choice. I like the flexibility and the fact that they don't just hire anyone, it creates a better atmosphere because you don't have anyone who doesn't 100% want to be there, and everyone is always on their game.
Perks weren't explained to me, but I know you don't get gratis as a freelancer, however they will do things for people so that they don't have to purchase an upcoming collection they are working a launch for. A girl I met works as a freelancer in Orlando and she gets samples for all of the events if she goes in a few days before the event she's working. Otherwise they have you come in early before the event to put the look on and I'm assuming you use testers.