Sketchup plans for small basement studio in NJ

After reading Rod Gervais' excellent book and checking out much of Ethan Winer's valuable information I have come up with a possible design for my basement studio using "SketchUp". My studio will be in my home basement which has a cement floor and cinder-block walls. I would like to record acoustic music in the studio - jazz, folk, etc... The wall and ceiling construction will be 5/8" gypsum dry wall, double layered with "Green Glue" in between. On the ceiling I'm planning to use RC-2 to hang the double sheetrock from the ceiling joists. I am allowing approx. 2" for floor construction which will be 3/4" strips filled in with some sort of foam filler then covered with 3/4" plywood and some Pergo-like laminate flooring. The ceiling from the bottom of the joists to the cement floor is 7'1". With the ceiling sheetrock in and floor installed the room heighth would be something like 6'9". I am using a contractor to build the studio for me. He works alone so progress is slow. All he has done so far is reconfigure some of the heat ducts so that they run inside the ceiling joists and feeds into the control room. There will be an intake vent at the bottom of the back wall of the control room. The triangular space in the corner of the recording room is where our water meter is located. The wall with the wide two panel frame is to (1) enclose the heat duct, (2) enclose the circuit box that is located in the control room (3) enclose a basement window that is next to the circuit breaker box. The irregularly shaped room in one corner I'm planning to be a vocal booth or string bass room. Problems that I can see with my studio design: 1. How to deal with support beam that crosses from the main room through the control room. Will it adversely affect the ability to hear an accurate stereo image and if so, how can I solve the problem? 2. How to treat the ceiling in the recording room and vocal booth with the least amount of ceiling heigth loss. 3. Is the vocal booth large enough to be comfortable? Worried that it will be too claustrophobic in there... I was going to put a soffit around the heat duct that runs through it. 4. Is a single solid-core door (1 3/4") with good seals sufficient sound isolation for the vocal booth? Any comments on this plan would be appreciated as I am hoping that framing will start next week. Here is the link to the Sketchup file: http://www.sendspace.com/file/2i6t26 I am just learning how to use SketchUp so pardon the roughness of the assembly. I realize that the control room as seen in my SketchUp file is not quite symetrical but I intended it to be. Thanks! If you have any problems downloading the file let me know and I'll e-mail it to you.

have you contemplated the Tony Bennett approach and just make the room wide open and use gobos between the instruments and mix console? i think build a control room in this small a space and then hoping to get a good open feel for a full size grand piano, drum kit and string bass will be touch with the tight spaces. then make a good vox/isolation booth in a corner if needed. build a nice drum platform to decouple the kit from the floor. for mix down, maybe a set of heavy drapes to close off the "control room" will remove a bunch of the room from the mix desk.