@emma, Well, I am struggling with this

Whilst the idea of the forum seems like a good one, I can't seem to make it work on multiple fronts.
As you mentioned, each user would need to be in their own group and ideally this should happen automatically at enrolment. It would seem like the auto creation of groups with single user is not great. You can only define group names based on letters or numbers. I see there have been many attempts in the past to get Moodle to add this functionality, but for some reason it was rejected.
On the actual forum, it would seem like the Q and A forum would be ideal as I do not want users to post messages simply reply to a predefined question. Unfortunately, this doesn't seem to work with "Separate Groups" only "Visible groups", as the students do not get a reply option when the forum is set as seperate groups. (
Edit - I see that a post to "All Participant" will not be able to be responded to by users in groups, and the only way to do this is to post to "All Groups", but this only works for currently active groups, not future groups

)
Further, the maximum edit time for posts only seems to be editable at a global site level, so I can't stop users from editing posts on these specific forums without affecting everything on the site.