[@mercime Participant 15 years, 2 months ago]

=== At the bottom of a given post, I want users to be able to comment or start a discussion forum on a specific element about the building in the post. ===

Enable commenting from dashboard menu Settings > Discussions.

=== Can I assign forums to posts instead of groups? ===

Why? There’s already commenting in posts with threaded comments – if your theme is set up for this.