#2 and #3; The .pmd files are created when you use External Binary Morphs and  contain the morph data, so, yes, you do need them.  :)   However, I believe they still aren't supported in DAZ Studio 4.x, although Studio will happily write them when exporting Poser files (there is a script to load them for Studio 2.x and 3.x), so you may want to turn it off before you save if your prop is intended to be used in Studio.

Poser imbeds the geometry each time a prop is saved, so you would need to strip it out after your morphs are added.

I'd love to know #4, too,  as I have a few  items with modes about a half-mile up in space... :)

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