Early Planning

Hello, all! I could sure used some advice! I'm planning a small personal project studio in the basement here in Upstate NY. Three of the four walls are 75% below grade and noise projecting a bit outside is no concern for lack of neighbors. However, the 4th wall needs to be as "sound proof" as possible. The space is also irregular as I've had to take a corner out for mechanical systems (see picture). Even if it were a rectangle, I believe my room dimensions are not all that great. (Though, I've been reading modes calc graphs until my eyes bleed and I'm still not sure.) I hope to purchase the phase 1 materials early this March so I want to get ahandle on the best layout. Since the space is so small and I want to be able to track live/record jams without everything bleeding into every other mic, I've decided (wisely, I hope) to use some of the space to fashion small isolation booths to house amplifiers or maybe even one large enough for vocals or acoustic guitar. I plan to make a double stud wall (one wall alread exists) where I need the most "sound proofing". The other walls will just be double sheetrock (1/2" & 5/8") with Green Glue in between. The double wall will also be two leaves of sheetrock 1/2" & 5/8" with Green Glue in between. (I'm planning on three tubes per sheet for maximum LF absorption.) Right now I plan to used 24" corner stacks of either 705 or Roxul RHT40 or other similar material of between 4 and 6 pcf. as corner absorbers. I also plan to make the mixing end of the room as "dead" as possible. The last thing I was thinking of is maybe adding a few preformed 2x4 diffusors in strategic locations. Room Dimensions: L 25' 5.5", W11' 7.25" or 14' 8.75" (see DWG.) H7' 6" Drawing Information: When looking at the drawing, note that partitions shown in white are proposed and all others are existing. Questions: 1.) What is your impression of the overall scheme? 2.) Can you offer some tips to improve the sound isolation of the critical wall? 3.) What do you think about my idea for the room treatment?