Yes, using the Zone ligth setting is the right approach
You can also grab ZOnes with nice skymaps from the market place
The main directional light (sun) is defined there. and the Ambient lighting is also configured there from the Ambient Map or the Sky Map if there is no ambient map (this way you can use an ambient map different for lighting than the sky map).
You have 2 intensities in the Zone Light settings
- the Key light Intensity which scales the Directional Light contribution.
- the Ambient Intensity which scales the AMbient light contribution.
THe ambient map is what you see in the specular reflection over glossy materials.
A way to calibrate the intensity you want to use is that when ambient intensity is 1, with a perfect glossy, metallic, white, mirror like surface you should see the exact colors of the ambient map in the reflection (assuming no other source of highlights).
I think a good balance to start with is key light intensity of 1.0 and ambient intensity of .5 and go from there…
About the bug that you mention, i think i m aware of it and actually trying to address it this week.
Let me know if you have more questions,