SNR is better than in the blue region, normal with the better sensitivity of the ccd, SNR50 around 5972A.
Straight absorption are Na-D interstellar absorption, with a bump inside. "The bumps in the core of the NaI D-lines is due to two present components. One forms in our spiral arm, the other one forms in the next spiral arm. Typically this is a sign of a distant object, unless there are many interstellar clouds in the line of sight. But in this direction, this means that the object is located in the Perseus arm, i.e. at least 1.5-2.0 kpc from the Sun." by A.Miroshnichenko
I'm not a specialist of WR star spectra and i'm very surprise by this profile.
Note there is no intensities variations, observed in previous study on HeII4686, during the 9600s exposure. Continnum not normalized, just rescaled to 1