What is an approximate number of Tsugaru Shamisen players in the U.S?
Just curious 
Judging by book sales, we have at least 150, but no doubt there are more. That’s one benefit of Bachido. Over time, we’ll be able to find out how many shamisen players (or enthusiasts) there actually are. An actual record of this may bring awareness to the shamisen community in Japan.
As far as Masters, on the other hand, that’s a tough one.
Give me enough money and I’ll call you a master. 
Probably the most real level of a master is someone who is as comfortable with their art as breathing. Doesn’t come by often (unless you’ve been playing from an early age).
At some point, it would be interesting to find out how many proficient players there are, in order to set up official Bachido teachers. But for now, just getting everyone interested in shamisen playing is most important.
I would like to have an email contact list for all of the more advanced players.
This would be a good way for beginners to contact and meet other shamisen players in their area and hopefully help build a strong community.
what age would be considered early Kyle? 
Aside from those who are extremely talented (where they could be musical geniuses starting at any age), I would say… maybe 12 or earlier? Basically, once the mindset of “mistakes are bad” gets instilled upon them, ease of musical learning vastly diminishes. Adults have the fear of making mistakes (because all around them, they are told that “mistakes are bad”), and that mindset holds most people back from making music natural. When kids are young, there is no fear of making mistakes, so for them, there are no limitations. With no boundaries nor limits, they can learn music as quickly walking or talking.
Of course, that doesn’t mean adults (age 20~100+) can’t enjoy or excel at playing music. One can get quite skilled if approaching it the way a child does, and doesn’t get held back by a fear of making mistakes.
This is kind of our “big deal” at my family’s business, Toneway.com. There we try to teach people in the same way a child learns music.