BracketronUniversal Cup-iT II Mount with Grip-iT

Q: Can I turn the head 90 degrees to accomodate my TomTom GPS?

The head as well as the stalk rotates 360. I had an older model that broke. This is an improved model so I bought a second one as good products tend to discontinue while the crap keeps coming back.

Q: Will it fit the new 2013 Nexus 7? What is the maximum width? Is it sturdy enough for a 7 inch tablet?

I doubt that it will fit a 7-inch tablet. Maximum width would seem to be only 4 inches or so. It holds my iPhone with an OtterBox case easily.

Q: It doesn't seem to fit in a Prius, anyone have tips to make it work?

It has spring loaded clips to fit the vent on any car. Does a Prius have vents ? (You can google for how-to videos)

Q: does this attach to the garmin sandbag holder ball

I don't think it will attach to the bag. It has these grips on the back that seem designed to grab on to the vents of the air conditioning exits in the car.