Now if Strahovski would just let up on her morals, I could relive my Chuck fantasies as well.
I think it is kind of funny that Masuka and Yvonne were both on Chuck together and now they are on Dexter together. Masuka = Harry Tang from season 1 and some of 2.
Vogel didn't seem shocked when she was looking at the brain piece at the end of the episode but she also seemed to really have hope for Zach being what she was looking for so I don't think she killed him.
Quinn killing Cassie is plausible to set the frame on Zach. He may have thought the fact that Dexter was friends-ish with her would get Dexter's support in pushing through the evidence and linking Zach to it.
I don't see Elway being the brain surgeon. I could see him going crazy and killing Dexter now that Deb is going back to the force. I just don't see him having the skill set to be the brain surgeon.
I would say that Masuka's daughter could be the brain surgeon but Zach being in Dexter's apartment makes no sense from her point of view.
The Zach being in Dexter's apartment part throws me for a loop. I just don't see anyone really putting that connection together that has the skills to remove certain sections of the brain.