Here is my situation: New Modular House installation.

2000 Square foot Conditioned crawl space:
Polysteel ICF Foundation avg height: 40"
3" Rat Slab on 6mm vapor barrier

house sits on 2x 10 PT sill; I am sealing with great stuff foam between the sill and the foundation


My Questions:

Do I place a layer of 3/4" foam on the floor?

Do I retain the loose batt fiberglass insulation between the floor joists?
Is it worth the effort/expense to place radiant barrier (FBF) under the decking of the subfloor?

When I insulate the the rim joist area: Which is a better method:
a. radiant barrier (reflectix fbf) with Foam sheets cut to fit, to a thickness to match the ICF Wall?
b. Just use the foam and forget the radiant barrier

Thanks
John

Would Thermal paint work?