Neopor is a development of polystyrene, the idea of renewing the insulation is nonsense, these houses absolutely have their right to exist, important when you put the elements together pay attention to door and window measurements if you are skilled in craftsmanship and maybe have a mason at hand then there should be no problem. But do not underestimate the time factor I once dug through some of my reports I had some houses from 1986 the substance was really good after over twenty years the mess was with the owners’ own work nasty laying and gas water crap so if you are good at it then you can save quite a bit regarding the shell construction but make sure you have a proper mason with you All the best for the house construction