If you're going to track drums and/or loud electric guitars or live monkeys that can't shut up, go for the floating floor. If not, don't. I think it's a waste of money. I've worked in different condo-type-studios both with and without floating floor, and I've never heard of anyone complaining (they didn't record drums, though!). I myself work in a studio in a condo, don't use floating floor.
BUT - I don't like loud listening while working - AND - I use headphones a lot, especially when just editing. If you want and/or like really boosting your speakers til they almost fry, and your hair gets slicked to your head because of the pressure wave, then go with the floating floor/walls/ceiling.
As well, I don't like using voal booths. My workspace is quiet enough, and I think I get better connection with the performer if we're both in the same room, instead of having them go inside a small closet or something. But, if you feel like it's easier and more comfortable to use a vocal booth, then that's the way to go for you. I'm just saying that it doesn't have to be done like every other studio out there, just think about what preferences YOU have and what kind of work you need to do in this studio. Full-fledged rock sessions or just editing?
About equipment, do you have everything you need as far as converters and mic pre's and stuff go?