Check out awesome redstone and build tutorials as well as the mega build AlphaCraft series https://goo.gl/LMbZVf
Interesting build, although making the number of affecting tables adjustable (eg controlled by where one places the torch-key(s)) would increase utility.
WARNING: I have an extemely "grindy" playstyle; YMMV — if this doesn't seem fun to you, mine what you can from it & bin the rest.
Absolutely, once the room is up placing torches can give you access to all levels
Thanks for your feedback