Nice tank, stand and discus! Definitely get larger driftwood, I prefer the malaysian and live plants are definitely possible low tech with no co2. I do it! Crypts, anubias, red tiger lotus, narrow and wide leave hygro, and java ferns all do very well in low tech setups. I would take the rocks out. If you do add more driftwood, please keep in mind that if discus startle, they will act like a ping-pong ball in the tank. Do not put driftwood in there that they could poke themselves with in a ping-pong situation.
Debbi
Debbi