Did hide know he was a ghoul since chapter 9. I mean he opened his eyes.(pg. 22 I think)
In chapter 10 hide escape the clutches or loses the ghoul that was following him. (Pg. 28 I think)
So now I'm questioning everything
Don't worry about it. There are a lot of questions and theories.
Those details you pointed out were put there by Ishida-sensei, some are just for fun, but others might be important. So, it's great you saw them and shared them with us.
About your question, you might know by now, right? Hide was awake in chapter 9.
http://www.mangago.zone/read-manga/the_legend_of_sun_knight/mh/280826/Vol5_Ch18/pg-6/
Is that Sylvester in the background with his instrument?