Somebody correct me if I'm wrong but aren't metric bikes bars 7/8" generally and HDs are 1".
I noticed the bars on my Sportster also have indentations for the cables to enter the switch housings that you won't find on a run-of-the-mill round bar.
No not correct. Kawasaki for instance uses 7/8", 1", 1 1/8" and 1 1/4. Totally bike dependant.