Shed studio construction help required

*edit*...maybe this is in the wrong forum? I'm not sure if it should be this one or the studio design forum...can someone please let me know whis it should be in. Hello, I've been in the planning stage for my studio build for a while now and I'm coming up against 1 or 2 issues which I would like some help with. I have been scouring the forum for weeks but haven't found anything that answers my particular queries. I live on 4 acres in southeast QLD and have onsite a 3 1/2 bay Titan style steel shed, on a concrete slab. Neighbours are 60-70 metres away. I am planning on recording all sorts of music, so volume will probably be an issue *sometimes* but I have played in other shed music rooms that have been built using simple methods - carpet on the walls, standard pink batts in the walls etc and they have been quiet enough outside for me to know that a design using the principles of proper studio design - I have read Rod Gervais' book a number of times - will (hopefully) do better. I will do the bulk of the work myself - I have worked in the building trade before and am confident enough to attempt the building myself. My next door neighbour is a builder and will oversee construction when necessary and help at times also. I am intending to use approximately 2 1/2 bays of the shed to build my home/semi pro studio - room within a room design, single frame, 13mm fyrchek inside, acoustisorb or similar in the frame, and a different (not sure which yet) plasterboard wall connected by RC to the stud wall on the exterior side. I would do a double stud wall design but money is an issue - total budget for the built is approximately $7500au and I dont believe I could do it on budget using 2 stud walls. The size of the space I have to use is 7.2m(l) x 5.4m(w) x 2.7(h). The first question I have is to do with the room roof. Should I do a flat ceiling or gable the roof using rafters and a ridge - the maximum height of the gable roof will be approximately 3100, meaning a gain of 400 from the edges to the centre of the ceiling. It would be substantially easier to make a flat roof as putting the plasterboard on the top of the roof will be alot simpler - doing a gable roof means taking the tin sheets off the roof of the shed and will involve a more difficult work position. I would *prefer* the space to be one big room and monitor tracking via headphone but I am considering the option of making a control room separate from the recording room. I am asking about the shape of the roof as I am wondering if the change in shape from a rectangular box to a gabled room is significant enough for the extra work involved in terms of acoustics in the room and the necessary treatment required to tame nasty reflections, etc. If the room has a flat ceiling at 2.7 high, I understand then unsymmetrical smaller rooms would be better than a large room in terms of controlling reflections and isolation. My next question, somewhat based on the above, is whether splaying the 2 outside walls would change the answers to the above questions, and if so, how much splay would be necessary. i hope I have explained myself enough, and thank you very much in advance for any replies.