The Original Squeegee

Yes you can change the rubber.  There is a video about exactly how to do this.  

Window Cleaning Tips: How to Change your Squeegee Channel Rubber

This really depends on how often you use the squeegee.  

Professionals change their rubber (or rotate before changing) every couple of days, but they are cleaning 100's of windows.  

Chances are with the quality of the rubber and normal household use, you won't need to change/rotate your rubber for months or even years.  

You can tell when you need to change the rubber when the sharp edge appears to be worn and when streaks are left on the window.  

In the end, all of our professional grade squeegees achieve the same result. A streak free window.  

Between the different pro models, it really comes down to comfort and preference for the job.  Some people work in colder weather than others and a ProGrip handle is less cold than a brass or aluminum handle.