Help designing a practice space

My house is being renovated and i'm getting a new practice space! yay! out of the deep abyss of a basement. Trouble is, the room needs to be quiet... not necessarily in the interior of the house, but externally. If you look in the design, out the window behind the drumkit is my anal-retentive neighbors, who have, in fact, complained about me sneezing repeatedly after sniffing pepper at midnight (don't ask.) the room needs to be pretty well externally silent. The second goal is to keep it as quiet internally as well. It would be perfect if I could just shut the door there and no one in the rest of the house would hear me. Building the room especially for soundproofing is also mostly out of the question, as this house will potentially be for sale and houses with music rooms tend to not sell well. So any internal modifications need to be semi-permanent to removable. these are the official building plans (albeit not blue). as you can see, i'm going to have problems, especially with 1) the furnace room right there, in orange, and 2) the vaulted ceiling. Unfortunately, this addon is above my garage and therefore will need it's own air. also, due to it being a top floor, the roof will need to follow the line of the rest of the house, meaning the exterior walls will be about 6' high (shorter than i am, damnit!) at the exteriours and vault up to 9'. I've outlined the area i'll have to work with in red. the potential setup of the room is in purple, with the drumset right in the window (it's my love...) and guitar/bass amps on either side. I plan on placing a computer with some recording software in the room to do some scratch recordings (i realize nothing i do in the room will ever sound nice, but a computer to get ideas recorded to is what i'm going for.) What i need are ideas of things i can put in the room to help minimize noise. I've got plans for a drum riser (see thread in the contruction board) and possibly similar risers for the guitar amps, and i'm thinking plexiglass sheilding around the drumset (and maybe some office cubicle boards in the room to help deflect sound). Also some reallllly big heavy curtains on that window behind the kit. Anything else that would help?