On the 6th point, I haven’t suggested this before, because I’m not sure it works for all SN posts but it could be relatively simple to implement.

On the ‘hot’ feed some older articles could be elevated with “1 month ago”, “1 year ago”… mentioned above each post. Limited to a maximum of 1 anniversary link appearing per 30 results each day, for now.

Might be a nice test to play around with. Easier to accommodate than a ‘revisited’ feed. Simple because there isn’t enough space up there in the menu anymore, as the site grows.