Not that technical communication is a communicable disease, but some of the points you ponder (e.g., "Could a person be bitten at a restaurant, return home, and then turn into a zombie?") sound more like the points explored in a mathematical inquiry into the spread of SARS.
Pictures like these two seem to be more in line with the model you are hypothesizing for the zombies:
You might find the article from which these pictures are linked, "Predicting the Path of Infectious Diseases," interesting.
Personally, I think you need to know more of the "rules set" operating on the zombies. I'm not convinced that they have exposed the behavior of the model enough, at least as much as I read about it.
Or, it's possible, I suppose, that you are assuming/imposing behaviors outside of its rule set.
Or, perhaps, not unlike the distributive property and adjectives and nouns, network models and zombies just don't play that well together. :-)