Either in the related questions list (with very high weighting) or in a separate list, it would be useful to show questions that link into the currently-viewed question.
In addition to seeing posts that link to other posts, it might also be useful to see external links and/or search terms. I have several posts that, for whatever reason, seem to get a steady stream of upvotes and I'd like to know how people are finding them.
I agree. I was about to post a request to support linking questions together as a form of "follow-up questions" but decided that it would be overly complicated for something so simple (or, if you like: it breaks the KISS principle.)
Your suggestion is more intuitive though.