With respect to Norman Similas' presence, I can only repeat what I was told by the late researcher Tony Centa, who lived near the part of Toronto that Norman Similas was from. Tony had a bootleg copy of the Zapruder film, which he got from Penn Jones. When he mentioned his interest in the case to a coin collection shop, the operator of the shop said that one of his customers was there at Dealey Plaza (he was referring to Similas). Tony eventually got into touch with Norman Similas. When Tony told Similas that he had a copy of the Zapruder film, he invited Similas over and ran the Zapruder film on his projector in his basement with Similas present. Tony told me that Similas got up and shouted, "There I am!!!". I don't know where or who in the Z film he was referring to. Supposedly, Similas gave a negative or copy of his photo (of the TSBD) to someone he thought was from the Toronto Telegram newspaper but supposedly it was an FBI agent who visited him in Canada (the RCMP interviewed Norman Similas on behalf of the Warren Commission, and they had that agent in one of their police cars and asked Norman if that was the guy who approached him for the photo negative, to which Norman said yes). Tony explained to me that Similas embellished his story a little as to his position or proximity to the limousine and therefore, lost some credibility.
P.S. A good friend of mine told me that his next door neighbour at one time was THE Norman Similas, who talked about the assassination all the time. (That part of Toronto is known as Thornhill. Tony Centa lived in the adjacent district called Richmond Hill.) Technically, this area is north of the official City limit of Toronto and is part of a separate city called Vaughan. Maybe I should pick my friend's brain if he remembers any more details that Mr. Similas may have shared with him.