SharePoint provides the user profile service to access this type of information.
qRules has a command called GetUserProfileByName, but this command relies on SharePoint's User Profile Service.
So, bottom line, whether you access via rules, via code or via qRules, you'll need SharePoint's User Profile Service! Here are a couple of links to get you started.
http://www.harbar.net/articles/sp2010ups.aspx
http://technet.microsoft.com/en-us/library/ee721049.aspx
Good luck!