Customizability of the environment

I have a few questions on what is possible to customize in the environments. If it is possible, could someone point me to the file that I would go to do that customization? That would be very helpful.

1. Where exactly would you go to edit the themes for the maze? Can you create custom themes by uploading images to be used as the sky / walls / floor?
2. Can you change the walls / floor of specific areas of a maze? It seems like you would use the variation layer for this - can you make it deterministic?
3. I'm assuming no but just confirming, are there sounds in the environment? The agent can only receive visual input? Is there any other established way to simulate other senses?
4. I have seen #68 , but I don't quite understand how to use the DEBUG.CAMERA.TOP_DOWN. With this would I be able to visualize an episode of training from the top down, just not use it as an observation input?
5. Can you extract the locations (x,y, direction) of agents over time?
6. Can you program events in the environment when certain events occur, such as when the agent goes to a certain location?