Thread:If watching this page/thread, do you get notifications where applicable? (by e-mail) (22)

That sounds like a bug if that changes the watch state of the parent page.

If you click on the from part of the a fragment of a discussion from User talk:KTucker (meaning the User talk:KTucker part of this example) you will be taken to the Talk page. If you click on the tab to the left of the Discussion tab (which might be Page or User depending on the namespace) you are taken to the parent page that the Talk page belongs to. The Watch/Unwatch setting is beneath the disclosure triangle to the right of View history (or has a tab heading to itself if you are using the old Monobook skin).