Yes, it uses CUPS according to the HPLIP system requirements.
Letting a garbage proprietary driver configure your system for you is perilous. Did it tell you what changes it made? Can you even uninstall it now? HPLIP might be the place to start asking.
The other linux users are also using HPLIP. I do not think I will be able to uninstall it. Also, When I try to print a test page, i get only half page printed and the other half left blank.