Ok but the movie poster claims “the most bizarre murder weapon ever used” and that’s just not even remotely true. Killing someone with a truck is real fuckin basic. You kill someone with some Pumpernickel bread and maybe you can claim most bizarre murder weapon.
System Mastery 
I disagree about the bus, it illustrates several important things:
1. He doesn’t have power over the kids, so of course they are crappy to him. That is how he views the world, those with power shit down, and those without power are shit upon.
2. The truck of course helps the bus because the truck is a ‘real man’, all jokes aside, it does illustrate his impotence, at least in this situation.
3. Even though he knew what would happen when he tried to push the car, because he “couldn’t be a man” and stand his ground, his car does get stuck under the bus. It is the punishment he deserves for being nebish.
This movie sounds pretty good, great job as always.