The connection with MC's bag and what was said on TV is meant for the reader to draw a connection between the circus and the disappearances. It's kinda obvious now about what's happening with pink tickets (we had a whole bad ending telling us what it was) so I don't see a need in explaining. It's also quite clever haha.
Aww making OCs is great! But you are right about the eye colours... I have noticed this but never really thought about it. Most of them match with their outfit but Pierrot's is different from the start: it's supposed to be white but Neko decided to make it red, and the colour red is also for MC's name and sometimes for Doctor so I'm guessing to avoid confusion, it is yellow. I think it's mosly about design purposes and I can't see why it would hide a meaning... It's a pretty and fitting colour if I do say so myself. In fact, Neko has said that Pierrot's attire was actually different in the story but then it had to be changed.
Thanks for bringing this up! And do not worry about your English; you type pretty well ^^ (Hi fellow European!)