9/32"? 11/32" is the standard size for #8 nuts and hex head machine screws, but 9/32" doesn't correspond to any standard or semi-standard fastener I can identify. #4 is 1/4", #5 and #6 are 5/16".
Yes. That's why he's suggesting the sockets in that size would sit around the warehouse for quite a while.
We did discuss this once though. Something in the past used that size. I think it was electrical cabinets or something similar.