Gin doesn't know that Shinichi is alive, otherwise Gin would have captured Ran, possibly Shinichi's parents, staked out the Kudo mansion or done anything else to find out where Shinichi. You try to argue this in all threads, but Gin thinks that Shinichi is dead. We don't have a single line of dialogue where Gin ever suspects that Shinichi is still alive, even during the Halloween Party he doesn't think that Shinichi could be alive.
Conan hasn't figured out the Boss. How would he have?
Highly unlikely. There is no indication for this, no hint, no nothing. There was even a joke question in one of his Q&A's whether Mitsuhiko is a shrunken teen too and Gosho laughed and exclaimed "No way!"
Why would you think that Rum is a shrunken person other than just throwing stuff into the room without any evidence, indications, hints or anything to back you up. Making stuff up that just sounds cool, but has no substance whatsoever, isn't a good thing to post honestly.
1. He knows because Kir is under observation from the BO, as Gin explains during Black Impact:
2. Kogoro heard the shots of Akai and reacted to them. He didn't hear the shots of Chianti shooting out his dish, because the window was closed and he had the television on a very high volume. Plus, he was pretty engaged in that horse race and probably spaced out watching it. Plus², does incompetence coming from Kogoro really surprise you at this point?
3. Yes, Gin wanted to kill Kogoro, but Vermouth talked him out of it later. I don't know what's supposed to be unresolved about that.
If anyone who is not from the BO calls, texts or tries to investigate through official channels, then the BO will track you, hunt you down and kill you. It's Pandora's Box because once you open it (call it in that case) they'll be onto you and it will bring misery to your life. Conan for sure hasn't texted the boss or talked to him, it would much too dangerous as he and Haibara conclude during the episodes "Big Adventure in the Eccentric Mansion"
Stop making stuff up, it's really annoying.