Q: Will vintage feet advertised for the models such as 66 99 127 128 201 221 222k 185 192 fit on my 15-91?
A: Yes, all the machines you mentioned are low shank, side clamp machines.
Q: My Pfaff 130 came with a box full of presser feet marked "Pfaff" and various numbers. Will they work on the 15-91, too?
A: Maybe. I have some that do fit the low shank machines. I don't know about all of them.
Easiest way to find out is try them on and see how they line up.
Joe