Hmmm....
Some of the questions were a little vague, and some of them kinda depended on what type of zombie you're dealing with (who knows what kind of symptoms would occur in a real outbreak, but as far as the cinema is concerned, there are numerous kinds of zombies that work on different levels). Because of that, since I collect zombie movies and have seen lord-only-knows how many, it made it a little trickier for me personally, because it's harder for me to think in the context of just one type of zombie lore. But, as you mentioned, trying to cover all the bases would be impossible, so I just tried to think along the lines of a Romero-type outbreak.
However, the questions do force you to think, which is excellent. I don't think I've ever taken a quiz where I had to actually sit for a minute or so on some of the questions and rationalize about the choices.
The grading confused me a little, but apparently Z+ is a good thing, and that's what I got. XD Overall, awesome quiz - best zombie survival quiz I've ever taken. :3