you’re absolutely correct on your first point. It would be TEN, BUF, KC 1-2-3. I don’t think the Chiefs will lose both of their last two games, though, unfortunately.
To your last point, it would come down to the 3rd tiebreaker, which is common games. https://www.nfl.com/standings/tie-breaking-procedures.
If that is also a tie, it goes to Conference win percentage (gulp).