Hi Ben
Dont let zbrush confuse you, zbrush generates maps in a funny way, the displacement map you have created is not a uv map but a displacement map. if you create a uv map in zbrush it will show up in the texture box, if you create a bump map it will show up in the alpha box. Dont try to learn to much at once as you will go around in circles.
If you createuv map in maya import it into zbrush with your model.

No I have not posted t zbrush.................dave