JoeMoe, welocme
while not an acoustics expert I have had some experience with ceilings that are also floors. Ideally (if you have room, I'd frame in a lowered ceiling that provides a dead air space between the two. Insulate both, more dense in the lower sealing
If that's not an option, bass is the hardest control, so I'd opt for a 4" rigid fiberglass (rfg) pushed tyo the top of the joist cavities so there's an air space below, then resilient channels, drywal... The green glue hype sounds good... don't actually know anyone who's used it.
I would then add some diffuser panels on the ceiling, , fabric covered RFG can be done without a frame, rock wool will probably need a frame.
If your resources allow, a hardwood floor is recommended over carpet, as I'm guessing you won't want bare concrete. I went with bamboo, not as tough as wood, but looks nice and I use area rugs under the drum kit and the keyboards (velcro on the bottom of the sustain pedals keeps them from sliding around)
If you don't truly need the center wall 9non-bearing) I'd probably remove it and maybe put a control room on one end with some utility closets for storage of gear
let us know how what you decide and how things progress!
and pictures!!! (before, during and after!)