Joe "Ko-Ko" Coyle was a longtime Chicago event clown and that he is most likely the person pictured at the far right of the Alley shot, bending down, with the pancake hat. The clown standing next to him was on the Cole Bros. Circus and appears (along with Emmett Kelly, Otto Griebling and Freddie Freeman) in the short film HERE COMES THE CIRCUS.
Other than that, I don't know who is who, which is which and what I can add.
That train looks pretty cool though, huh?