Best place I've found for documentation on the guts of the cr2 (and similar files), is BL Render's "Secrets of Figure Creation with Poser 5." Despite the name, it is basically a under-the-hood look at the core structure of joint parameters, welds, etc. common to Poser from Version 1 out. It also explains other goodies like ERC, easy-pose, body handles, etc. On the import/export. I never remember which settings I use, but I'm sure I've stumbled upon a combination that lets me go into Carrara and out again. I have discovered, usefully enough, that if I import an .obj at Poser scale, I can scale up in Carrara 600x to work on it, then reduce to 1/600 before exporting, and it actually seems to go right back to the same spot (at least, close enough for me!)