I use a protector for the back. It does offer better grip than with no protector. It is a wet process of applying, It comes with full body protector. I only used the back and sides of the protector...
I have the Scosche MagicMount dash/window. Bought it at Cosco, came with two mounts and a car charger for $39.99. I have the magic plate attached to the phone case, works fine.
Cell Phone Holder and Tablet Mount | MagicMount by Scosche