Sci fi model, import from sketchup

Hi to all, i’m trying to make some sort of sci-fi short movie, so i draw this “spaceship” in sketchup and imported it in blender:
I tried to import in both modes; from the .dae file and from the .obj file; you can see them both in the second image; (.obj in foreground, .dae in background). The Collada .dae file seems to retain the original shading i give in sketchup; but once i render everything turn half-black/half-texturized (third pic). In both import i have to remove duplicated vertices or lines; and in both cases the result is not what i like. Especially the dark corners around the windows angles