the sky is blue because of the refraction of light between the ozone layer, and it disperses the red and green colors from the spectrum. The sun is yellow to us, because it mixes with the refracted light from our ozone. otherwise, it would be white, and the ozone layer would be a cyan color.
OH
It's just some stupid thing that's going on, where if you are beaten by someone who is a vampire or a zombie, you become infected. The only way to be cured is to be decapitated.