Wow, what a question.

Well, don't paint it white, that would be bad. I'd go with a mid grey as with the right lighting you can make that white or black. Darker is better as you can always add light but it's hard to control light bouncing all over the place in a little white box.

Sounds like a very small room for a studio, I use Profoto gear myself I think that would be over kill. Get yourself down to the Flash Centre and try out some Elinchrom gear. They do a really great try before you buy service and will be able to give you specific advice on what you need.

If you are really serious about colour rendition and consistency then Broncolor or Profoto are the pro option but be prepared to shell out A LOT of money for it. I don't even want to think how much money I've spent!

I'd also make sure you have a decent wireless trigger system, in such a small space cables will soon become a real pain.

Cheers

Cris.