Re: Zombie Science, that's just it - most zombie movies don't HAVE to worry about that stuff, since the movie's over in two hours.
Here we have an opportunity to really take a good look at how the world will remain dangerous in a reasonable time frame. It's been (I think) less than two months since the outbreak in story time, and the population has already been decimated - we just aren't seeing much of the people who've been made into neural chow, where we probably SHOULD be seeing many more skeletons and remains of the devoured. I believe that the comics establish the changes in zombie behaviour and ability as the rot and winter set in, but that may be spoilerish.
And speaking of a darn fine poke at how zombies work despite a lack of food, I'd always recommend Max Brooks' books for a great analysis on the many topics...