Instead of going with mavic open pro rims, I would probably get mavic A 719.
I've used tubus racks and they've worked fine for me and I haven't ever heard anything bad about them.
I'd definitely use ortlieb because they are waterproof and not as expensive as arkel.
Downtube and bar end shifters are basically the same thing, just mounted in different spots. I prefer bar end
If you are worried about bars, you could get some bear spray