your askng for LOTS of problems with a wood floor. why not just pour a concrete floor,,,like a garage floor and bolt the walls down to that, no animals under,no rotten floors,no crappy insulation. put 2" Styrofoam under it and its all insulated as well as some plastic. Did I see the price somebody was quoted?? Completely off there rocker. guess maybe I better go back and read better. Houses never used to cost that much!!!!
I see your point 4just1don, but I'm wanting the wood floor for two reasons.
First, this structure will have a deck/pergola off one side and I want the building to be up at that level.
Second, it will have a lot of music/electronic equipment in it and I want it a little elevated in case of catastrophic flood. My last music studio was in a basement that was dry for ten years until a massive ice storm here in OK clogged the storm drains. The next hard rain came and flooded my basement/ruined equipment, We don't do basement well in OK and in fact any house built after about 1935 won't have one.