Select the node you want to change to another type and change it, appearing on the top left on a mobile device as in the screenshot or top right on a full width screen.
It's an odd position for UX as you'd expect "change" to be lower near the type set (circled). I believe I already made this suggestion, but doesn't appear to have been added.
That's not possible. It's either a suggestion thread or a question thread and nothing shifts the most upvoted/downvoted around. The only way to achieve this would be directing the user viewing the thread to sort them by votes or affixing ?order=vote_score to the end of thread links in a template edit somewhere (custom development if you are seeking for help).
You can see the sorting for this thread in action here (I upvoted your last post so it will be at the top when clicked on):