Thank you for pointing those out. I actually had the same thought earlier. Anyways, I've added this paragraph in regards to your first point.

"Why did the miners not spread the disease to others? The novel coronavirus is most contagious during the early phase of the disease, probably one to two days before symptom onset. The miners were only taken to the hospital when their pneumonia had become severe. And mask-wearing was probably widely practiced in hospital settings. Therefore, the coronavirus at that time might not get much of a chance to spread."

And about the complementary gain-of-function theory, it's largely a speculation. I've also heard (although I did not verify) information that China was reluctant to share information about the pandemic and quickly put the blame on the Huanan market, but these are another topic altogether.