I'm on the B73 out of Casa so can't really help on the nav front, but just to say that you probably want to stay clear of Casa, not much to see really. A long the beach front is ok but in summer will be crazy busy with lots of beggers. Casablanca is the biggest city, but i would say it's the Birmingham of Morocco. There are better cities to visit. If i can help feel free to get in touch, we regularly stop over in Marrakesh..hotels..etc...
Gareth