I can confirm that the above is exactly right. Only actual stack leaders will get those type of V&Vs. Some vices will affect a governor and, not always the highest ranking general, if he's in a province when something occurs is he's in a separate stack. I've noticed this quite often.

Yesterday after capturing a rebel province and executing the rebels, a governor of another province that was part of that army but was not the general, gained the "scant mercy" vice. I've also seen governors and generals in separate stacks gain the steward or builder vices simultaneously when in the same province, it doesn't have to be the highest ranking general nor governor for that particular province either.

The moving around thing, I'm not sure about, but the shielding with a higher ranking general does work. It's not the sitting about that seems to cause all those bad vices, it's leaving your governmors in a province or inside the fort exposed as a stack leader that's the problem. Initially they'll do well, as far as v&vs go, but after a while something bad is going to appear and stick. I've never had a good high ranking general yet that didn't eventually get something nasty such as "glutton" or "crack brained" or whatever else.