I'm of the opinion that you can be flexible on the powers/abilities of a vampire in order to fit the vampire into the narrative you're creating. If an element of the myth doesn't work for your storyline, chuck it. Bottom line is to come up with a good story that you like.

I think the big ones to work with are blood drinking and nocturnal activity, but there's a lot of explanations for those behaviors that can be used.

I've been in a couple different vampire-themed RP's, but the one I am currently doing requires me to decide just what is and isn't the case with the abilities of vampires, and so this is an interesting discussion to keep an eye on.