This is one element, but the tsuba is also used to protect against the opponent's blade, which is why it's made of soft metal so it doesn't break. In Katori Shinto ryu, there are several techniques using tsuba.
Most likely. They are minor smiths, so there are no examples of their work in the literature, which makes a declaration of gimei hazardous. That's not to say it's not a gimei, only a shinza shipment will tell, but is it worth it?
越前住宗次 Echizen (no) ju Munetsugu. According to the literature, there are 2 generations working in Kanei (1624/1644) for the shodai, and Kanbun (1661/1673) for the nidai.
All that i can say is that it is impossible to see if this sword was suriage or not without having it in hands. All that you say is pure speculation
https://www.nihontom...articles/Suriage.pdf
In science, all it takes is one example to disprove a theory and they are not so rare specially in some schools . Back to the sword in discussion, suriage or not, is has the sugata of a kinnoto (勤王刀).