Bare bottom is definitely the best way to go for young discus. I've seen breeders over here doing massive daily water changes of 80%-90% with bare bottom tanks. That way they can feed messy high protein food to get maximum growth rate without having to worry about water quality.
In regards to the lighting. Since you are running UV you don't have to worry about green water and can run the lights for most of the day if you like. A bright tank is good for discus as it prevents them from peppering up (developing black dots), especially for predominantly white discus.