As an aside, I think there was a study on caffeine where they put people with varying levels of caffeine tolerance through a series of performance tests with and without caffeine, and it showed that even people who had built up a high tolerance and didn't consciously "feel" the effects of caffeine still experienced the same performance benefits of the caffeine. Sorry I don't have the details or the reference (so I can't speak to the robustness of the study), but it's out there somewhere.

The information travels via waves on the electromagnetic spectrum, which in theory can travel an infinite distance unless something interferes with it (reflection, attenuation, etc). It's just a matter of time for it to travel whatever distance it needs to go.