bkay

I'm guessing your question about "parts" is about the what the extra feet do. The feet do the same thing on all that era of sewing machines. Download the manual for a Singer 15-91 and it will tell you what the parts are for. They usually include a foot for sewing a zipper, doing a rolled hem, etc.
bkay

edit: The 15-91 manual is just a more detailed manual. There are several differences in your machine and the 15-91, but the feet still do the same thing.