Building new studio in Sweden. (more info)

Hello I have been watching this forum for many years as a guest but now I need to share my thoughts with you guy's. I have been working as a technician/musician for 15 years and been thru some studios. Right now I have a studio in my home or rather a seperate house on in my garden. It not a big studio it consists of two rooms a controlroom 23 sqm and a recordingroom almost the same size. Now I have plans to move the studio to a house that I might buy. It's much bigger, 18 mtrs x 9 mtrs. It used to be some sort of communityhouse with a big room, 90 sqm, for gatherings. It aslo have a kitchen, toilett and an unused entrance. I have made some basic drawings and plans for how I could convert the house into a studio. I want to keep a big live room. The big room would be about 85 sqm 10,6 mtrs (35foot) long and 8,4 mtrs (27.5foot) wide with a 3.7 mtrs (12foot) celing. The controlroom would be 27 sqm , 6,41 (21foot) mtrs long and 4,45 mtrs (14,6 foot) wide with a 2,6 mtrs (8.5foot) celing. There will also be a kitchen next to the controlroom and above an area of about 30sqm for bedrooms and lounge. The rooms have to be soundisolated and acousticly corrected and I feel that I need some help there. The roof in the big room is angeld on the sides about 1,5 mtrs up from the walls. The walls are 2.7 mtrs high. The top of the roof is flat and about 70 sqm. The floors are wodden planks on wooden beams. My plan or the big rooms is to build a new wall about 10 inch from the existing wall and to have two layers of drywall and one layer of fiberwall, so all in all 3 layers the same goes for the roof with the exeption that I might not buld a new wooden frame to put the drywall on. I would put the drywall directly on the existing beams. The controlroom is another thing. There I plan to put neoprene pads on the existing woodbeams and then put a flooting floor ontop. Since im al little short of hight I want to keep it as low as possible so I want to skip the woodbeams and just use chipboard directly on the neproene. On top of that I was planing to put two layers of hard drywall to give som weight. The walls will stand on the floor with no connection to the buildingsstructure and the same with the roof. I might need to put som hanger in the middle of the roof to make it work so the roof dosen't fall down. I will need someting to hang it in that dont transmit the sound to the building structure. My budget for the construction is about 20,000us dollars. What do you guy's think? I need more detaild buildingplans before I can start to build of course but would this work as a start? Something you think I have missed?

Just added some more pics

I forgot to mention that the building is an old brick house built with doublelayerd brick and a wooden framed roof construction.