Shawn -
I'll only address the stuff I have experience with:
1. I would not suggest tile flooring. What do you currently have? If it's cement/smooth concrete, you're in good shape. It's easy to paint over, there is no pattern in it (with tile, you're stuck with the tile pattern no matter what you paint), and it holds the paint well. A tile pattern under chroma green would be a nightmare to pull a key from.
4. Sonex is the real way to go, but there are way cheaper ways to soundproof - any music supply house has a generic acoustic foam - try a Google search on Sonex, then on Acoustic Foam, and see the price differences. Also bear in mind that if you have a curtain in the studio, you may not need the acoustic treatment, since a curtain absorbs a lot of bounce.
5. You may want to just use a combination of light blocking venetian blinds and light blocking curtains, just in case you run into a situation where you actually want some natural light.
That's my two cents. It would be a good idea to discuss budget, as Mark mentioned. You don't want to cut corners on quality if you have a real budget - but then again, there are some places where you can get the same results for a lot cheaper than the high-end options.
Joe Bourke
Owner/Creative Director
Bourke Media
http://www.bourkemedia.com