I DO believe that Heller had Red John picked from the beginning. Writers create an interresting story at the very seed of beginning with a connection between protagonist and antagonist that is not revealed until the sleuth uncovers the killer.
Where the PI eyes looked would indeed have been relevant in reality to discover height, but not in a scene where the door was open (a prop?) and there was probably no one on the other side. The actress could not have anticipated our obsessive ponderings. However, when she struggled with the assailant, she looked up. I wondered about the discrepancy. And Visualize did NOT hire her, Cho put words into her mouth and she agreed with anything to not be arrested and still protect the client.