Hi Quentin! I am currently building the Roden Ni 27, which is essentially the same kit, so I will be watching your build with interest, as we are at about the same stage.
My kit seat broke also, so I made a new one from ten thou sheet styrene. The Tom's seat should work well also.
Your struts look great! My only suggestion is perhaps replacing the tiny locating nubs with brass wire. I did this, and it's a little tricky, but makes for easier and stronger upper wing attachment. I did not do this on the Roden Albatros DIII, and it was a real adventure getting the top wing in place. The plastic nubs just do not provide enough positive fit to secure the top wing.
I'm also interesting in how folks attach the lower wings to the fuselage. From Jacek's photo, it looks like he used a brass tube insert to accept brass rod pins placed in the wings. How is proper dihedral established in that method? I'm leaning towards using a brass spar through the lower fuselage with holes drilled in the wings. This approach has its own problems, including getting the dihedral right. Has anyone just used the plastic nubs and glue?
Sorry for the mild thread hijack, but it does all relate to this kit and build.

Regards,
Bob