About the rust?
I'm erratic in my opinions about the movie, sometimes they're positive to an extent, sometimes very negative, it certainly wasn't FANTASTIC but it wasn't as bad as is often made out.
about the coloration: didnt some manual somewhere (WC1?) note that the material used in the Kilrathi ships was a reddish Durasteel that gave it an almost rusty color? Could not a similar material be used in these ships?