Wow! It's looking great! And yes, I've actually thought about making a mention to folks using layered sprites to use that since I've had a few people come back and ask how to sort it out.
As for using a variable to adjust the lighting, you could do it with a custom written transform that accepts a variable parameters instead of hard coded ones. I'll be working on another pack on stream this week, so I'll put some time into getting an example for you to play with on Tuesday!