I hope I have filled out my profile correctly. Hoping to get some advice on a build I am yet to start but I have my design up to a reasonable level, sketchup screenshots attached.
I am a producer, though not professional. I do not play drums but do make a racket with my guitar, various synths and mics. My neighbours do not give a monkeys, the house is fully detached and they have parties all te time anyway. That said, new neighbours may be less understanding. My main concern is the bleed of noise into the room above, which is a bedroom. As such my overall attenuation target is going to be what I can achieve with the ceiling, most of the rest of my measures are to prevent flanking routes for noise to reach the room above.
My room is 4.6m (L) x 2.6m (W) x 2.7m (H)
The long walls are both brick cavity with no fill, as is the section over the garage door. The rear wall is concrete render though I am uncertain of the composition behind.
You will notice a strange void under the floor in my diagrams, this is an old inspection pit that will be filled with concrete before screeding the floor, then laying my DPM and tanking that to the DPC and laying celotex on top. On top of the Celotex will be an engineered wood floor. I wonder if there is any practical use for a void underneath a studio space before I go ahead and fill it. I can't imaging it would be anything other than trouble.
My outer stud in the old garage doorway will be built off of a new concrete footing and the screed will lap up to this. The inner stud will be built on top of the screed. I will also be building a stud wall at the back of the room, again on the layer of screed, where my plug sockets can be surface mounted to noggins.
As the room is rather narrow I do not plan to stud the long walls but instead to use a resilient system. Reducto clips offer the smallest profile, I believe these are an evolution of the Isomax design. Unfortunately, doing this will prevent me from hanging new ceiling joists without suspending them from the brick walls, which would obviously be pointless. As such I am limited to a resilient channel system for the ceiling too. I am less worried about losing height here so will probably go with genie clips in this position. Essentially, the resilient system on the walls and the internal stud on the back wall are only being installed to prevent flanking noise reaching the room above. The rear wall is a kitchen and the internal side wall is a hallway.
There is an unfortunately placed window on one side wall which I plan to replace with double glazing and then make a plug that will stay there indefinitely (keeping the window will be a plus when I eventually move out.
I plan to replace the garage door with a double 4"x2" stud wall from the floor up to a new window that will span the width of the garage door. This double glazed window will sit on the outer skin, cavity bridged with rubber and secondary (sliding) glazing placed on the inner skin. I would like to integrate my ventilation baffle in the stud wall if anyone has any guidance on that. I don't need help with basic designs just wondered about the logic of containing the assembly within the stud work.
So, my questions:
1) I have been trying to find an appropriate equation to ascertain the bleed of sound through a window of given size. I plan to put a very large window in the garage doorway and I wonder how the quality of the window, thickness of glass etc compares to just reducing the size of the opening. Light and the feel of the space are very important to me creatively so I would prefer to up my glazing spec than decrease the size of the window.
2) Should my resilient clips, reducto clips in this instance, screwed directly to the brickwork provide adequate isolation such that the transmission to the room above is primarily through the ceiling? I know this is a "how long's a piece of string" question but I wonder if my plan makes sense in principle.
3) I do not have room for a door to open out of the room into the hallway and have come up with a plan to have two doors that BOTH open into the studio space. Ie. the outer door is smaller, in a smaller frame. I did consider cutting a fire door in half and making a bifold door in the outer frame but making that airtight would obviously be a total nightmare.
4) I noticed that the guys over at genie clip offer an alternative clip installation pattern to support up to 3 layers of soundboard which feels like a good idea but this pushes me from 34 to 52 clips and to my mind that is just going to make the spring stiffer so to speak. I wonder whether this would hinder rather than help.
5) Green goo. The suppliers in the UK seem to regard green goo as snake oil. They recommend instead to use tech sound. I know it works in a very different way but it seems across the pond the techsound is seen as the snake oil and the green goo is the sh!t. Just wondered if anyone anywhere had done a direct comparison (not holding my breath on that one).
6) Is there much point trying to fill my existing brick cavity with insulation? This would be an expensive solution but one with no impact on the size of the room. There are potential issues with doing this in an older property but I wondered if rockwool or similar would have any impact in my situation.
7) The stud walls I am putting up front and back will be lined with 60kg rockwool, some have said that the cheapo fluffy stuff is actually better and that just melted my brain. Really not sure who believe any more. Any recommended products?

I think that's it for now. Thanks in advance. If I have posted in the wrong place or the wrong way do please redirect me, I'm new here.
Bests, Jim