How to see "How often do people log in"?
Drupal Views - CiviCRM integration will let you combine Drupal data (e.g. Username, Role, Last Login) - with CiviCRM data (e.g. Source of Contact). I've trimmed the screenshots to strip out CiviCRM Sort Name, and Email address for privacy reasons. 

To figure out who has logged in in the last 2 months - would then simply be a Filter on User: Last Login; If you'd like to filter by Group -> you can do that here too;

If you don't already use Views -> in CiviCRM Core -> Administer -> System Settings -> CMS Database Integration;