More on the stability: I think you're right about Josh's relationship with Bartlet.

There is something of the difference between father/son and father/daughter here, too. If you look at Josh, Sam and Charlie, all of whom Bartlet sort of adopted (as did Leo with the first two, of course, and in the season one extra it totally cracks me up that Martin Sheen and John Spencer can't agree who plays the mother and who the father), they all occasionally voice disagreements, absolutely, but only up to a point. I can't imagine any of them doing something like giving Jed the "these people need their hotel rooms and the roads cleared of your motorcade and I need you as a president, not as a charity worker" speech CJ does, or make a statement like "I'm dissappointed". (Charlie perhaps, but that's stretching it. Definitely not Josh.)

Now, Toby would have been a miserable CoS, but he always seemed to be the foreign policy heavyweight to Josh's domestics.

True, but do you think he'd be able to get through one meeting with the chiefs of staff without pissing them off? Not to mention he wouldn't have been able to write anymore, which would have increased the general Toby misery considerably.