Unity Camera Follow with Freelook and Collision

If you're familiar with the camera from any 3D GTA you know it follows the target as it moves and if you move the mouse, it overrides the follow order and implements freelook rotation around the target with no nuisance key pressing until a timer passes and you've not mouse looked at anything new after which the camera is subjected back into its original follow mode. Also it has predictive collision and moves the camera smoothly out of the way before impacting/clipping a wall. I know unity has all three of these features, but I've not yet found a single asset to do even two correctly. Can someone please show me how this all can be achieved?