Can’t speak to all of this, but:
- There is a setting to “disallow deleting posts older than x.” The default is/was to allow users to delete their post for 1 year. You may wish to adjust this to prevent deletions at all.
- You may also wish to look at the “Ninja edit Window.” This allows a member to edit their post within a few minutes of the original post time without having the changes show up in the edit history. This is primarily so you can fix typos and such. For your use case, you may want to make sure every edit is visible in the post’s history.