Hey.
As you already acknowledged, FBX support is only in latest devbuilds, as well as OBJ support, for static models only. I never tested both formats since MD3 is fine to me. For a proper downscaling, you need to scale the decoration scale, not the scale in Model Configurator. Need to note that you can go below zero, like 0.5, 0.1, 0.05 and so on.