Ground-up studio concerns, please help!

I am having a room within a room studio built in my backyard, and we are creating the structure from the ground up. I would love some input on my current plans, and have a few questions that I really need to address. Both the exterior and interior walls will be framed with wood on a newly poured concrete slab. I have been unable to find much information about how the exterior walls should be created.The plans for the exterior are to hang paper and wire mesh on the wood frame, apply lathe and plaster, and then 1 inch stucco. I am worried that the stucco will not be an adequate sound barrier without an additional layer of plywood or some other material. Does anyone know if this is the case? There will be a one inch air gap between frames, with a mass-spring-mass configuration including insulation in both frames. The interior walls and ceiling will consist of two layers of 5/8 drywall with a layer of soundboard sandwiched in between. I had planned to hang the interior walls on resilient clips with hat channel, but I have read that it would not help since I will have completely independent framing assemblies. If anyone could clarify that for me I would greatly appreciate it. I have also considered forgoing the soundboard and using a damping compound such as green glue instead. Would this give me a better STC rating? At this point, any mistakes in the design would mean that I waste all my money. I want to be able to record and have my band practice without disturbing the neighbors, so the higher the STC rating I can achieve, the better. Any help would be greatly appreciated!

could you post the plan drawing? do you have to do stucco?

Here's an illustration of the exterior and interior walls. I did not include the resilient clips and hat channel because I do not believe they would benefit me with my already decoupled walls. At this point in the process I don't think I have much choice to use stucco, but if you have alternative suggestions I would love to hear them! Thanks, Jesse

one option would be exterior plywood outside and under the stucco, and then line the inside of the plywood (between studs) with drywall to increase its mass. brick or block as the outside wall might also be an option with stucco over that...

What is that "sound deadening board" you talk about.. ?

Just a standard soundboard. I have actually decided not to use it, and use green glue instead. Everything I have read comparing the two makes me think green glue will give me better results.

good thinking ;)

one option would be exterior plywood outside and under the stucco, and then line the inside of the plywood (between studs) with drywall to increase its mass.

This is what I'm going to do. Great idea!