you have to reapply the texture file in med. then it won't be black anymore.

the scale should work but usually you have to use much higher values like 64. in blender the units usually are more used like meters and in 3dgs more like inches.

...
i already have a new exporter which directly exports textures and supports the new model features but since the resulting models only will work with 6.4 i haven't released it yet.