The back touchpad shouldn't be your concern, more the touch screen. I can't answer all of the questions but it comes down to how much you appreciate handheld gaming over the big screen. If you don't like to hold a small unweildy handheld with a tiny screen, PS TV is the best possible option.
That's the exact reason why I will get a PS TV day one.
Gravity Rush will definitely not work with TV unless they patch it to be used with the DS4.
If you demand respect or gratitude for your volunteer work, you're doing volunteering wrong.