Nice shots... The extender with glass is probably a 1.4 or 2x teleconverter. I've owned a few copies of the 55mm Micro, including a couple early compensating 55/3.5's with the metal focusing ring, then three later 3.5's, as well as four 55/2.8's. Currently have one of the 55/2.8 Micros. With the 55/2.8, at f/22, you can get a sunstar effect if you take a photo with the sun in the frame.

With respect to the Nikkormat, I have the Japanese home-market version of the FT2, the Nikomat FT2. Great old beast...

-J