This episode, all of the Glee writers were there to judge who they could write for. From what I understand of traditional casting, the actor already has a defined role to try out for, and it isn't what they're like in real life.
There were five contestants left, and in the end two went home, Lily and Michael. Next week it will be between Blake, Ali and Aylin. It was interesting that the writers said that with a character with a disability, the disability was the least of the things they focus on about the character -- or something along those lines. I'll have to listen again. It feels like to me that Blake would be the one that would be the most a blank slate as far as playing a wide variety of characters, because he wouldn't be hit right away with viewers' prejudices.