Studio design advice requested-new construction

Hello, My name is Byra Ferkovich. I am building a new house in Florida and will be building a studio in half of a detached garage. The plans for the whole house, including the garage/studio, are almost done. I want to be sure that the space I have created for the studio will be optimal, especially now before any actual construction begins. I have ordered Rod Gervais' book and have been reading this site non-stop since I discovered it. Im addicted! I plan to use the studio for both band rehearsal space and recording and mixing. I would prefer to not have a separate control room/live room because a lot of the time I will be recording myself and I think it would be easier and faster to have everything in the same room. I also want to 'waste' as little space as possible so there is more space I can actually use. However, if this is sonically inferior, Im open to building separate rooms. The space as currently designed is 32'x18'x10'. The building will have a 3 car garage on the other side of the studio and a loft/bonus room upstairs. The 32x18 room will need to include a staircase to get to the upstairs, a small bathroom, the studio itself, and an isolation booth. There will also be a door to the outside and possibly a door to the garage. The house will be out in the country, so soundproofing for the neighbors' benefit is not an issue. I just want a room that sounds good and is good to mix in. Since the construction has not started, I can change dimensions easily now, ie a higher ceiling or a wider room. For the budget, I havent settled on an exact number. However, Im willing to spend whats required within reason-perhaps 10k or so beyond the cost of the basic room itself. Maybe more if this is way too little. I just dont know how much this stuff costs at this point. My first and most critical questions are: 1) Is having a room above the studio going to impair the sonic qualities of the studio? 2) Is there a major disadvantage to not having a separate control room? 3) Is the 10' ceiling high enough? I realize that this depends on whether the room is divided into a CR and live room or kept as a big room as far as the ideal ratios go. Ill work on drawing the basic layout of the room in sketchup. It should be attached now. Thank you in advance for your advice and help! --Byra