With the parameter "Sub Geometry To Use", you can reference the FBX file twice and have a different renderer for each FBX sub-tree. Did you tried that solution?
About the group id: for the moment the group id is defined by the data (i.e. the order inside the FBX file). However, you can reach more complex behavior by applying a function mask:
(here I showed with a "custom" function, but you can also do all kind of stuff with parametric functions...)
For sorting along XYZ axis or radially, I see no simple solutions and we can't spend that much time on this for the moment...