Thanks for the interest, and being so thorough. I do hope to share my result here, so that this can be part of an on-going conversation. I'm not sure about how subscribing works on HN, but I'm currently considering making results available through an edit to the original post of this AskHN. Hope that works!
Here are other thoughts and questions I have for your points:
2 - your point about rituals needed to shape an offline community is fascinating, do you find that there are any adjacent rituals for online communities?
3 - I hadn't realized that quality degrading for links, but not comments would be a pattern that arrives but would love to hear more about this if you're willing to offer more details!
5 - can you say more about the 'stay below a threshold to continue to attract users who have more to offer' bit?