When editing my user profile (name, date of birth, etc.), how can I tell which information can be seen by other users (publicly visible) and what is only used by the system (and how it's used)?
The easiest way is to open up your profile in an incognito browser session.
Things that are visible to everybody:
Things visible to diamond moderators only:
*mods have to click a link to see this information, the act of which is also logged.