Khajiits can use their tail to pull the string?
From a biological standpoint, I can't accept that.

they have the shape of a cat, and a cat doesn't use its tail like a monkey. They use it mostly as communication device and balancing tool.
Anyway, I agree with Badprenup. It's utterly impossible to use both bow and sword at the same time. At least, as long as you want to use both for their intended purposes.
Furthermore, red dragons do already exist, but they're VERY rare. You only meet them in the main quest. I also think there are already enough ancient ruins, tombs, whatever. There's only so much you can encounter on the way while keeping it believable. And I've always seen the walls where we get our power words and where a dragon sleeps on as a "nest". Dragons don't really seem to follow the normal reproduction rules, as Alduin has resurrected them, so I'm not sure whether they need a mate and a real "nest".
Harder dragons would indeed be pretty nice. But i think everybody already agrees on that.
