Hey there, so first off you'll have a lot of luck googling the following. "site:skoolie.net subfloor insulation" (or whatever else you're looking for), from here I like to go through the image search because pictures are more fun than words.
That said I'm in a similar boat as you are now: Insulation choices.
I made a thread a few days ago which you can find here
, where we discuss this topic.
Here's my short opinion.
I intend to use XPS insulation for the flooring because of it's rigidity, Polyiso for the walls and ceiling. Spray foam is better for walls and ceiling, but it's pricey. Avoid using great stuff spray foam because it's not designed for metal.