You can do it either way- Rename the original first, then save the new model with the old ones name into the same folder where the original is supposed to be, thus being able to just use the original CR2. Save the new model with a new name altogether, open the CR2 file in a text editor, the nchange the Runtime:Geometries line to reflect the new model. When you open Poser with the second method, and open the Clothing menu, you'll get a shruggy dude until you add the new clothing to the menu. As for the textures, yes, you apply the new texture templated image to the new model if you have completely re-mapped it.