If you look in the .iv file you'll see how it works: You need a spotlight (IFAICS directionalLights don't work), the cutOffAngle and dropOffRate control how the shadows look like. There is more info on http://coin3d.bitbucket.org/Coin/classS ... Group.html
Implementing this FreeCAD-wide seems not specially difficult (one just needs to "encapsulate" the whole scene inside a SoShadowGroup object and add a ground plane, maybe modify the default lights too), then there could easily be some setting to switch that behaviour on/off.
About the other features, I haven't looked much yet. Fog seems easy too, same system ( http://coin3d.bitbucket.org/Coin/classS ... nment.html
), mirroring I don't remember exactly how Jürgen did it, but I think it involved copying all the scene contents... As for advanced texturing, that's a whole more complex matter, it involves implementing stuff at object level, and will ask for mch more complex controls...