Moved to Server Administration where these resources can be found. Please review any of the posts related to custom admin reporting with Tableau server. Check out the links here -Tableau Server Resources
for monitoring Tableau Server and then also be sure to check out the many resources that users have built related to custom admin views. This is a great start - Tableau Server Admin Library - Code on Github
I hope this helps. I'm sure others will jump in with more details now that this post is in the server area.
Yes, those are in Tableau Server's postgres database. Just google "Tableau Custom Admin Views" and you'll find info on how to tap into the data.