You've done it again peach bomb 😊. You put the rest of us to shame - this is longer than any three of my posts, and probably more interesting besides. It deserves much voting up!
Have you read Luna - touches on some of your main themes here, but its got a corporate edge which is a bit annoying. It suggests re bone density that there would be a timeframe beyond which inhabitants of the moon would be unable to return to earth. It also suggests that those born on the moon would never be able to visit earth.. As a plot device it works, but there would obviously be technological solutions if that really was a thing... But who really knows what kind of adaptions would be made to people after life in space..
Brilliant post.