For the user points thing, you can simply read them from the `qa_userpoints` table. Do a join on `qa_users` to get the usernames.
For example, to get the highest scoring users, run this query:
SELECT u.handle, p.points
FROM qa_users u, qa_userpoints p
ORDER BY points DESC
The user points table has all the various stats, which you could use to display those leaderboards if you wanted.