I would like to know if it possible to copy an existing screen like Customer Maintenance, so I can then create a new screen only displaying the Customer and Credit Information.
If not, is it possible to make the Credit Tab on the Customer Maintenance only available to certain users?
You will want to customize the screen to look the way you want (possibly saving as a new customization).
Then, create a new menu (if applicable) and assign the new customization to the new menu.