It isn't quite the same, but marking viewed posts as read and automatically hiding viewed posts seems to do the trick for me

Yeah, this one gets me too, occasionally. Maybe a resume button would be simple (if the state still exists) and work well without being too obtrusive.

Normally I'm browsing from Home, hit Back accidentally, and then try hitting Home again but that forces a refresh of Home (sometimes? Always? Can't remember).

This happens to me fairly often so I’ve been wondering as well. No way that I’m aware of

Thats the neat part!