sound studio conversion

Hi Everyone I've just bought a suburban house that has a separate brick (hollow grey concrete blocks) and tile studio building out the back which I am converting into a working sound studio. I would like to track bands/drums/loud cabs etc as well as quieter acoustic instruments and singer/songwriter types. I also want to be able to have a decent control room to mix in as well. The facility would also be used for film sound design/post-production from time to time too. My goal is to track music day/night without annoying the neighbours at all if possible. I realise that this can be both difficult and expensive but like everyone I'd like to achieve what I can within my resources. I currently have $3500 to spend on the project. I will be doing all labour/fitting myself (with friends working for beer/studio time). My priority at present is to soundproof and treat the central tracking room. Once this is done I'll be looking to soundproof the adjoining rooms as well. The roof has timber joists with terracotta tiles. The control room already has a ceiling (flat, not pitched) but no insulation as yet and also has a hollow wooden floor. There are wooden slat mezzanine levels in both the tracking room and the guest room- there is a helical wooden stairway to it in the tracking room. Both the studio room and guest rooms have concrete floors and both require a ceiling- I have obtained Knauff Earthwool R3.5 for ceiling insulation and propose to put up a ceiling of 2x 16mm CSR Fyrcheck (with layer 2 covering joins in layer 1). I propose to keep the pitched aspect of the ceiling to avoid introducing another set of parallel surfaces into the tracking room- the long parallel walls unsurprisingly have a VERY nasty flutter echo at present, untreated. There will be some Earthwool left over for panel treatments. All external doors are currently glass panelled and all internal doors are your regular hollow internal doors. First I will need to replace the double external doors in the tracking room- I am proposing to replace with solid wooden doors and attach a layer of 16mm Fyrcheck on them. I will need to source appropriate door seals also. The long walls in the tracking room require treatment- however I like a live room and I dont like the idea of deadening the space too much. I have obtained some cuts of wood from a wood yard that are from the outside of tree trunks and so naturally/randomly curved- I propose to mount these on slats mounted onto the wall with insulation behind and between the off-cuts- I realise this is unconventional but I got the materials for free and think this may be both cheap and effective to act as a diffuser/absorber. Ive attached a small sketchup of this for feedback. In the long term Im thinking of building an Iso/vox booth beneath the mezzanine in the tracking room in the corner next to the door to the guest room- but other stuff must come first. I have attached a sketchup file of the building (which is mostly to scale :wink: ) The studio building is 3m from my house and at least 12m from the closest neighbour. So to the questions: 1) Will two layers of 16mm Fyrchek gyprock plasterboard be fine for the ceiling? 2) I did have an idea of attempting to de-couple the furring channel mounts for the ceiling (attached to the ceiling beams) with 15mm rubber but wonder if I'd just be wasting my time given that the ceiling will be contacting the walls... what think you... ? 3) Will my plan for the double doors (solid doors with 16mm Gyprock and door seals) be enough for the external doors to the tracking room? 4) What considerations do I need to take into account installing the doors to enable me to also install great seals around them? ie. ideal gap around door to fit quality seals in? Can anyone recommend a door seal setup? 5) Is my idea for tracking room parallel wall treatments a good idea? and 6) is my current plan for floor layout a good one or are there perhaps better ways I could utilise this space? Any help or feedback anyone can offer on my current plan is most valuable and appreciated. I was going to go ahead and do it next week but after reading lots of posts on this site realise that its better to get the advice BEFORE I commence the build. I offer my apologies if I have left out anything. Thanks in advance Gordon