As to the original question of the threading/size of NJS components, take a look at the (ot) Campy 1991 catalog which states:
"special threading for hub,bb,crankarms,pedals and headsets must be used to guarantee interchangeability with other existing equipment" on the Record Keirin NJS approved group page.
It doesn't appear that the NJS stuff has any super special qualities, rather it is done to: 1- restrict equipment to the local manufacturers 2- create an even playing field among competitors
Len Diamond
Ridgewood, NJ USA