Excuse my ignorance but if I get some fpv goggles to fly with my phantom 4 what can I control with the goggles ?  does the head movement only control the camera up and down ? or can i program the unit to rotate the craft with my head when in course lock thereby having full control of the camera ?

I have only used the litchi app for my fpv goggles.  Litchi only tilts the camera.  I understand there are a couple of other programs that will also yaw the drone, which will pan the camera,  but I have not used them, and have heard they are quite buggy. The Dji GO app currently has no provision for even controlling camera tile, or even using fpv goggles.  That may change when the proprietary wireless fpv goggles for the Mavic is released.

Litchi & Android controls the camera and drone