Yup that all makes sense.
So, in all the the various 2/3/4 gene colours, if pp is present (rather than carried Pp) the eyes are red, no matter what else is there? Actually that makes a lot of sense doesn't it, as red is the mutation and black is wild colour - so the p mutation is affecting eyes (causing red eyes) whilst the other mutations just don't affect eyes.
I forgot about the ruby-eyed mottled - isn't that only in the US though? From what I've read Mi is the ruby-eyed gene, with the anopthalmic white problems, and that's in the US, and Mo is a different mottled gene, that doesn't affect the eyes at all, and that's in the UK?
Linda Price's site gives a good rundown of all the different mutations, with piccies
but I always manage to find more questions when I read about these things.