Can I ask a dumb question to those smarter than I: Is this way of visualizing temperature/pressure accurate, or is it an abstraction for convenience in the same way that depicting electrons "flowing through wires" is?
Yes.
To clarify, it's a useful model, but a model it is. One that makes reasonable assumptions about idealised and simplified conditions.
Relative pressure variations do not seem to depend much on number of particles, which seems counterintuitive.