4x6 with doors cut in??? Gonna be mighty short doors.
Trupan is a lightweight, medium density fiberboard, MDF. Any wood working tools will work fine. Like any mdf, does not deal well with water. The surface takes any water base paint, scene paint latex etc just fine.edges have a tenancy to absorb the paint (water) and swell up. Test your paint on a scrap. I have been told, no personal experience, that a solventbase spray paint will seal the edges.
Like any MDF, some degree of framing will be needed, the board doesn't just stand up by itself. Stiffness is dependent on the thickness and the framing.