Plans and Practical questions concerning Irish Studio build!

[leski]

Hi, in the next few weeks I will begin building the studio. Attached, I have included an outline of the proposed structure. The thick black lines are 2 leaf structures. I am planning for 2 x layers of plasterboard, with a layer of Green glue. The overall thickness of the MSM system will be about 14". The thin black lines (booth and IGNORE ME IM A FACE SPAMMER of the CR) are interior leafs as there is a brick exterior wall that encloses the North and West sides of the building. The Height of the studio is about 3m (12 foot), although, (depending on the price) i might be able to go as far as 4 metres..which would be nice!
I am planning to house the computer in the foyer and use wall panels (usb, Firewire, dv Bnc etc) to provide connection into the control room.
Oxygen will be supplied IN from the north end of studio, (separate systems for live room and the cr) as that is the only practical access to the outside. Out Vents will take the form of velux windows above the Cr and The Live Room. I aim to open these between takes or at night, or as necessary...Not ideal I know (from a sound perspective), but at the moment I cant afford to duct properly. My thinking is, that in the future (when the studio makes me a multi-millionaire!), and I CAN afford proper HVAC. I can remove the windows and at least the holes will already be there...
This build will be taking place within another. much larger structure and there will be other artist spaces South and East of the footprint of the studio. So..questions....

1) I am wondering about the ideal insulation material on either side of the air gap. There is the standard rockwool here:
http://www.goodwins.ie/p-706-rockwool-r ... 576m2.aspx

or a cheaper, looser material that ive never used before called Earthwool, here:
http://www.goodwins.ie/p-30431-earthwoo ... 388m2.aspx

I have read on this forum that less dense insulation may actually improve TL between leaves, and as the earthwool is cheaper, and 'looser', Im wondering if this is a viable option?

2) Regarding the structure of the walls, my builder is insisting that we use spaced 'noggins' between the uprights of the wall to give the walls strength and to support them when we have to stand them (before we attach the plasterboard) - yet i keep coming across photos of studio builds with no noggins..just a wall made of uprights and stuffed with Rockwool...

3) do I need to use anything to keep the Rockwool in place in the wall (like a muslin cloth) and stop it expanding and moving about over time?
Obviously this would be more of a concern with a looser insulation such as the earthwool..

Thanks in advance for any replies..Im a real novice when it comes to the science of this...

Les