Regarding the nature of the zombie virus, FTWD does raise some interesting questions. Is it the mysterious flu-like illness that gives you the disease, then you turn when you die? That seems to be what happened to the neighbor (the man they shot in the face) right? He didn't seem to have any bites, but was seen coughing in episode 2.
I believe that TWD cannon tells you that the zombie bite has nothing to do with transformation, but rather it causes sepsis and death from infection. To me, that seems even more absurd in the early part of the epidemic because a.) freshly turned walkers would have the same bacteria in their mouths that humans have and b.) sepsis could easily be averted with rapid and aggressive treatment with antibiotics while the hospitals were still up and running.
I guess my gripe is that while the nature of the disease doesn't need to be that clear, it also shouldn't come across as unnecessarily contrived.