Thanks for taking the time to post that. There is a lot of good info there to pore over.
Regarding Guhapdo/Kuhapdo, have you seen any styles of this art in practice? Our Hapkido kwan practices a sword art called Cheong Seok Kuhapdo that is very heavily influenced by the Yamauchi-ha branch of MJER. I'd appreciate hearing about any other Kuhapdo groups you've encountered.
Most of us get our swords from Korea, from a smith in Seoul (through our teachers in Daegu). They're steel and hand-forged, and very nicely finished. We can get both iaito-type dulled blades and shinken-type cutters. They tend to be pretty heavy swords (my dulled one weighs almost 1,300g).
btw, since it's obvous that you've read a lot about this subject, you've probably heard that there are reliable historians who say that the smelting and forging technology that created the finest Japanese katana of yesteryear came originally from Korea.
That would be a nice subject for somebody's Ph.D dissertation.