Basically from what I remember, the wiki copies the summary on the back of the first volume and not much else. I probably should write up a background page for Rayflo since not everyone knows his canon.
Hmm...for weapons, unless the anti-vampire weapon Zero uses has been blessed with holy water or the bullets are made of silver (I think they are, but can't remember?), I'm not sure how it would work on Johnny. In many ways the vampires in his world are ex-humans, but strong like purebloods/noble vampires in VK. The only way he can die is having his heart ripped out or being outside in the sun without protection (which in Vassalord-verse, they do have super UV protection). And if any of the dust his body turns into from being in the sun is saved and preserved, he'll heal and come back anyway. Vampires are pretty hard to kill in Vassalord.
Johnny is a former human vampire though. He was not created in the traditional way of vampires in Vassalord-verse, as he willing allowed a curse to be placed on him to become a vampire (or at least that's how it sounds in one of the earlier chapters, the details are very vague on why Johnny chose to become a vampire and how). He sleeps in a coffin...which has dirt in it from a graveyard. He can go into churches though, so crossed and the like don't work on him (but holy water does). He doesn't need to eat regular food either, although he can.
Cherry is...special. Charley is not only a cyborg vampire who hunts vampires...he also is very religious, works for the Vatican as a vampire hunter, and is currently working his way up to Priesthood (and insists on remaining a virgin >>).