I went with the dark color depicted on the Datafile, but I agree that the reality was probably a lighter color. Some period reports described the Albatros aircraft as "banana" colored indicating natural wood. Anyway, I'm happy with the color I have and that's what matters (to me).
Regarding the observer's position and turret, let me be the first to say that it's clear from the available photos that there were several turret designs and even that the area around the turret was done in several ways. On the aircraft I models (and in the photos I was using as reference) the observer's turret is surrounded by shaped metal panels. But in other photos it looks like wood. The way I modeled mine, forward of the turret is a panel shaped from lithoplate. Rearward is another "protective" strip intended to protect the wood beneath the moveable MG mount.
Note: Mine is the CI not the CIII.