Does backup and migrate include the users and login info? I'm migrating from the test environment to the live environment, both of which have a separate set of users/logins/privileges. 

How do I not overwrite this information when migrating from one site to another?
If you want to move user data from a Drupal site to another, you need to use the Migrate module. The Backup and migrate module is for exporting and restoring database and files.