Add features to a custom drupal system

I had a programmer develop for me a custom drupal system / website. The programmer set everything up correctly, however I still need some additional work completed on the system. I need 5 additional user levels created. Since the Super Admin level has already been created and is working great, the other 5 user levels have a less and less roles and permissions. I also need to make some adjustments to the current notification system as well as adding a way to send a mass email to all or individual user levels. Anyone that is well experienced with Drupal and creating custom features for Drupal should have no problem with this project.