Can I Mute & Freeze my CommBox Panel on a input?

Yes, you can but these are two different functions. You can mute the screen by using the remote or the buttons on the front, bottom, right corner. 

On your CommBox Classic there is a Freeze app which is conveniently located in the tools menu for you.

The display screen remote has a 'Freeze' button and on a pulse remote the freeze is the blue button.