This is my first post on watchuseek. A little background, I've always loved vintage watches and have wanted a trench watch for quite some time as my first collection piece. I've been eyeing the piece below but have some questions about the movement. This is being sold as a 1910's Tavannes 11 jewel trench watch. There are a few red flags to me that I was hoping someone on here could address?
1) The seller has indicated that this is a 570 series tavannes movement, and that it is not unheard of in the 570 series to have 8-11 jewels. However, I couldn't find another tavannes wrist piece of the era, regardless of movement, that has 8-11 jewels on an extensive google search. The other issue I have is that the movement seems to be more of a 13''' rather than a 15''' (570 series). The reason why I say this is because the click on this piece is located directly next to the balance cock, and the only other 15''' that has the click next to the balance cock has 3 train cocks (15'''-6T, see below diagram).
2) A lot of the parts in the movement seem to be new, which makes it harder to authenticate. The post for this watch says that the movement is signed, but again I couldn't see any sort of signature.
3) The case is a blanches fontaines, which the seller indicated isn't uncommon given the Tavannes/Blanches Fontaines relationship that I guess dates back to the 1890s? Can anyone confirm this?
I'm just trying not to get hosed on my first piece and would love some input. I've attached images of the piece plus the Tavannes diagram I used when looking at different movements.