Maybe i should add something for clarification.
When i say "parts", then i don't mean module A is one part and module B with Solar panels is another.
Some of the models are made of 150 to 290 parts/ pieces, where "part" means, that the entire mesh is made of cylinders, boxes and spheres, which have a texture slapped on them.
This pic shows the upper part of a different Orbiter model:

Turning those parts into pofs will eat up your shipslots, and will drive the user into madness when trying to assmble the ISS in FRED.

Most Orbitermeshes are build this way ( from the model app, staright into Orbiter), for instance, there are high poly SW fighters with over 160.000polys. Made of Boxes, Cylinders and Spheres.
The ISS will be set up for assembly Module by Module in FRED, as originally requested, which makes the most sense to me.
I think that certain parts ( Solarpanels and such ), will also be available separately.
Openable Cargobay doors and a moving Canadarm on the Shuttle are possible.