I agree, there were quite a few (too many, it seems to me) instances of happenstance that appear to have brought all the elements together in Dealey Plaza for the assassination to have happened via a pre-planned conspiracy.
Among other things (like you, I have a long list), I don't see how Oswald could be framed, that the conspirators/framers could know where he was at 12:30. The rifle, the shells, the bag are all found
before his co-workers are interviewed about him. If they give him an alibi, if they say he was with them, then the whole plan implodes. And this is murdering the president not a 7/11 clerk. Everyone is going to be interviewed again and again and again. You can't keep all of these people quiet.
So how did they know this? I don't see it. What's the backup plan if they give him an alibi? The rifle's been found; do they just make it disappear? Make paperwork showing it belonged to someone else? How did that person get in the building?
It's a long long list of things to control, things that you can't. The conspiracists just say "the government" or "the CIA" and think that's sufficient evidence. Because the CIA did this or that bad thing they could do this bad thing. Guatemala, Arbenz, MK-Ultra, Castro plots and this. But this is not like those other things. This involves so many people, so many layers, so many things that you just can't control. And then cover it all up? Even now? No, sorry that's a view of a world that I don't think can exist.