There are plans for number 1, basically preprints: see Implement megajournal support · Issue #382 · pkp/pkp-lib · GitHub (my suggestion here Preprints in OJS3)
Number 2 you could achieve fairly easily with a plugin. This is a related plugin I made a while ago which shows the reviewer names. GitHub - ajnyga/showReviewers: OJS3 plugin for showing reviewer names for published articles (note that this is a proof on concept and not a refined plugin to use in production)
You could edit the plugin to make it show the reviews instead of the reviewer names.
For public commenting there is GitHub - ajnyga/disqus: Disqus plugin for OJS/OPS/OMP 3.2+ and GitHub - asmecher/hypothesis: A Hypothes.is integration plugin for OJS