You know how sometimes a person's hair generally bugs you, but then JUST ONCE it's exactly right? This is that picture. This is one of the times we just get to see his hair. It's normal teenage boy hair!
this bit makes sense, John thought maybe, MAYBE, Sherlock was on the mend; that he was on his way to being a normal human being. But now he can see the cold hearted thought process and he sees now how Sherlock has regressed. ---> THE FEEEEEELS