However, even with the content, there is no way to actually re-constitute a MediaWiki instance without some other important things.
2) each installed Extension at their respective version. This is harder to reproduce, but at least you get detailed information on the bits you need at Special:Version. The version info is also available through the API
3) the LocalSettings.php configuration file. This is not available in general for any wiki. The administrator would have to publish this. One way an administrator can make this available without also making your wiki insecure is to have an include named "PrivateSettings.php" which is included by LocalSettings.php. Put the application database credentials in 'PrivateSettings.php'. Exclude PrivateSettings.php from your version control and keep it secret. Add LocalSettings.php to your version control and publish it's contents.