Yes, dogs definately feed off our energy - if we get worked up, they will too; if we stay calm, they'll calm down. Not always, of course, but it certainly helps.
About the bus, there could be many many things causing that problem. Do the dogs bark/lunge at every vehicle? Maybe it's not cars, just diesel trucks? Maybe it's just yellow vehicles? Maybe they're barking/lunging at the kids because they don't like stranger's kids? Is it only when the bus is moving, or when it's stopped too? Do they bark/lunge forward, or do they subtly move backward? All of these factors determine what to do in this situation, which is why it's so important that people who are having behavioral problems like this with their dog consult with a trainer/behaviorist (or at the very least, post the situation on chaz!) to develop a plan to solve the problem.