Modifying Leads List View (Display Data and Assign Function)


I want to modify the Leads List View Page and I am not sure if this is possible because from i understood and I am not sure if I understood this right, all modules seem to use a generic ListView so if I modify that ListView it will modify all of the modules? I just wanted in the Leads List View, phone numbers and addresses will be displayed with X marks for example: (818) XXX-XXXX and 1576 XXXXX ST., XXXXX City. And where you tick checkboxes selected leads, not sure also if this is possible without creating a new module that when they click ‘Assign’ i will modify that function and will do additional process.

Maybe you guys can point me in the right direction on how to achieve this.

Thank You