Could someone explain how you would navigate back to the home point or R/C using the maps and radar on the Go App assuming you do not know the oreintation or location of the Phantom/Mavic. I know you could always switch to the Home lock mode but without using that what would you do?

If you use the radar, you do know where the Phantom is and how it is oriented.
Try it out sometime where you can see the Phantom, turn it in the air and watch the radar.
Move it across to your left and right and further out and see what that looks like on the radar.

There's actually a great video on the navigation system in the DJI Go app:

Right now the map is not working correctly with Go app version 3.1.0, so you'll be totally confused.At least with Android.

And when the red arrow representing the aircraft is pointing towards the centre of the radar (Home Position) it is facing you, and will head in your general direction when right stick pushed forward. Just watch the distance shorten as you get closer and adjust flight path as needed.