I believe the pz3 file effectively contains the figure cr2 file as it was in memory, so morphs inj etc.  There are other ways to reduce the info in the pz3, but Poser does not seem to use them, the same file format seems to run across all the file types. i.e a pose, mat pose, prop, figure , face etc all are subsets of the scene file.

 

If I have a commercial project that I must keep for future use, I burn the scene file , and all figures, props and textures used to a cd. There is a script supplied called CollectInventory (something like that) thats very useful.