Responses

I don't remember exactly why he repressed his own memories but I think it was like a mechanism of defense, because he kept see things in mirrors and having alucinations, and he was an orphan, so everyone thought he was crazy and criticized him, so he thought that if he forgot everything it would be better and he wouldn't feel the pain, so he made himself forget basically
No spoiler but (ノ≧∇≦)ノ
I assume the truth will be revealed soon (look at the raws) !
I think maybe both of them were swallowed by the mirrors. Is Jun really innocent ? I dont think so...
When they *hum hum* it's like they are "mixing" (sorry for my bad english), and maybe that's why Jun begins to act like Yeonwoo little by little...