Please evaluate this vocal booth I'm building

Hi, I'm a singer living in a small apartment and I'm building a vocal booth. I want it to be relatively soundproof (I want to be able to sing fully without disturbing neighbors and I want to keep noise (PC, conditioned air, etc) from coming in. I also want to treat it acoustically. I built a 40" X 40" X 80" steel frame for it (due to my lousy welding skills, the frame is not perfectly square, which I guess is a good thing). My plan is to install 2 layers of drywall with Quietglue Pro for the walls, ceiling, floor and door. The door will be a simple door (see 2:30: https://www.youtube.com/watch?v=ir01g2-pEQY) with thick foam that will make it shut tightly. I will cut a small hole to pass the mic and lamp cables through and seal it with putty pad (http://www.remo.com/portal/products/2/5 ... typad.html). Inside the booth, I'll put a carpet on the floor, hang acoustic blankets (http://www.vocalboothtogo.com/acoustic- ... tic-(sound)-blankets-for-sound-absorption---producers-choice/sound-blanket-producers-choice-with-grommets.-black-and-white/8-23#ja-pathway) and use them to round up the corners and put bass traps (http://canada.foambymail.com/MFBA/male- ... rbers.html). I'm still not sure how I'm gonna seal the drywall because I wanted to make it portable for when I move out but anyway). I wanted to know what I can expect out of this set-up, both acoustically and "soundproofingly". I'm really not a handy guy and just this will be a big hassle I'm sure. I also don't have a big budget (around $500-600). I might also get clips and make a resilient channel (http://www.soundproofingcompany.com/sou ... und-clips/), but in this case, if I want to use the Quietglue Pro, would I need a third layer of drywall? There wouldn't be no fan in the booth, at least for now, so I know it would be get hot in there. I'm using a Shure SM7B mic. Thanks!