I don't know of any type of can insulation for the walls. How about good old R-15 or 19 for the walls. Would be close or same as in your house. I would think you would want it to be warm and hold heat like your house.

As for the floor it it is wood on posts than I would think you would want to insulate that also. I know Advanta-tek 50 is one of the best subfloors you can get and would make a good base if you did go with a spray on bedliner type coating another choice only a bit costly unless you find some on a close out would be ceramic tile.

What type of heating system are you going to use?