Welcome back. 

Alot of things changed since Poser 6, most important weight mapping and Physics based render engine. 

As for printing 3D figures:  The slicer requires manifold meshes, i.e. enclosed volumes. Poser figure meshes are not manifold, so there's work to be done there. Fastest method is to make a render and use an image-to-3D function, for example https://www.krea.ai/3d to generate a printable model. I found it reasonably good at this.