You truly are a constant blessing at EastSide. I've always enjoyed your findings in the classic forum, and am glad to see you frequenting this forum.
Most of it, definitely, but Yukio Tani (who came with Uyenishi) also studied Tenshin Shinyo Ryu. Barton-Wright himself, who imported these guys, learned Shinden Fudo Ryu during his time in Japan. Then you have to add the wrestling influences that came from so many challenge matches and practicing with Armand Cherpillod. There was a lot of eclecticism going on at that time.
Frankly, I never knew of these "ronin" practicioners, interesting since they all have seem to have been imported by this guy Barton. I truly wonder if they are real hard men or masters of the art. During the same time , even earlier, Kano was dispatching his top 5 students including Maeda (Gracies teacher) to spread Judo to the world but these guys can be traced by ranks from the kodokan and real badasses with ties to ambassadors and govt. officials
It's a tricky question. The Kodokan sent a representative to Britain who defeated Tani in straight jiujitsu. On the other hand, Tani was doing hundreds of challenge matches against local wrestlers in music halls (and I believe a few boxers as well), some of whom had studied Taro Miyake's book on jiujitsu and knew a little bit about what to expect. Very few people lasted the full fifteen minutes with him without getting submitted. You can read about it here: http://ejmas.com/jalt/jaltart_Noble_1000.htm
Awesome! It may sounds strange to say this, but I was suprised that it looks practically identical to the techniques I was taught early on in Ju-Jitsu, I don't know why I expected anything to be different! Good stuff.