Look up Layers in the manual. You can assign each level to a named Layer, and assign its lights to that same Layer. I haven't tried this particular scenario, but it should work properly.
You can colorize elements further. Split into individual layers and/or use mask layers. Then use use color adjustment clip layer(s) of your choice. Couple of themes from me:
Update 3: Ground layer has been updated with shadows and mountains,
stars and moon have been added to upper layer. Final adjustments to layer
position on model have been made