Can I restrict access to the app for only some of my Salesforce users?
Yes, you can do this through modifying permission sets to app components (Custom Objects, Tabs, VisualForce Page, APEX) by going to Setup > Installed Packages > Opero Fax.
Yes, you can do this through modifying permission sets to app components (Custom Objects, Tabs, VisualForce Page, APEX) by going to Setup > Installed Packages > Opero Fax.