Insulation, Radiant and Vapor Barriers - insulating floor on elevated home

Since we live in the flood plain, our home had to be elevated 10 feet. Now, we need to insuate the floor. We looked at spray foam (closed and open), but was told when all the moisture (water just 100 ft from house and with the possibilty to have water close to the floor during a flood) it was not reccomended plus the cost was high. We think fiberglass insulation is the way we will go. My question is what R value to use (there are 2X8 floor joists) and should we put up plywood underneath the insulation to prevent critters from making homes and help with preventing air flow up the floors? If we used the plywood would it help lock in the moisture under the floors and cause mold? If there was a leak on the main floor (hot water heater goes bad, bath tub/sinks overflows) would this cause a molding problem? After this is solved and done, what about the cold floors. The heat runs are in the ceiling since the house is in the flood plain. There is a section underneath the house that will become a garage thus that are will have underpinning(walls). However, a portion of the floors will be exposed to the elements since it is 18 ft off the ground (the house sits on sloped land) and we are not going to underpin it. Radiant heat in the floor is beyound our budget. How about the electric baseboard heat that is suppose to be radiant? We would greatly appreciate any advice since is is cold outside and we do have saved bucks to get this done!

I don't know where you live, but almost all houses around here (NC) are built with crawlspaces, which is not much better than having an open system like you must have. I'm pretty sure all of the floors around here simply have fiberglass batting up between the floor joists, with the little wire hangers holding them in place. This won't give you warm floors, but it will make them warmer than the probably are now.

I think that unless you totally close off and heat the underside of the house, then you need to be carefull and make sure the area can breath to avoid the moisture issues you mention.

*** I'm not a contractor or expert, just sharing what I've seen in my area***