insulation options exterior/interior metal building

[genuine]

I have a 40 foot metal sea container that I want to modify to allow the space to be used/ airconditioned.

1) is there an exterior spay product that has signifigant R value to be worthwhile ?

2) any recomendations on how best to ventilate. A friend had suggested building interior walls with the 1.5 inch polyeurathane foam panels. I'm confused as to how and where to run ventilation ducts and if a four inch duct has any value as I'm trying to keep "walls" thin.

For example if the main "out" of the ventilation was in the middle and there were two ducts running 15 foot from open vents, is the fan for 4 inch going to have enough draw to do anything at all...?

The long sides of the box face the southern and northern exposure. I know that the south side is the most important for keeping insulated/ keeping cool. Does it make sense to have that wall/ insulation thicker and the other side thinnner so as to maximize the usable space. Like if the southern side was 8 inches thick and the northers side 4 inches thick is that a better use that six/six?

Painting the exterior roof white is an option to reduce the heat issue. Would it be better, (that much better) to try to add some reflective material like a 6mil mylar...?