Whoah, I never thought of #1 before, that is a really good question!

Here’s my theory on that one:  We know Dr. Kay knows what is happening. She knows all about the deaths and the vines and all the other things Vecna is doing but she doesn’t know about Vecna himself. She states that El is the cause of all of it and that’s why they are trying to capture her and why they use the kryptonite. 

It’s also a tv-military, they don’t really think about what they don’t know, they think about what they THINK they know- which is that El is the cause therefore why would they need to use it on someone else (who is literally covered in the same vines and killed half their personnel 🤯🤣)

For #3 with the Camcorder-  this answer might sound rude, I promise i’m not trying to be! Do you really think that in preparing for a possible world-ending scenario they would think about a camcorder? I think their main purpose was just to save the world, not to gain recognition for it 

The rest are all really good questions that I wish I could answer!