I doubt that the glyphs are actual powers stolen from dracula. If anything they're spells stolen from his library possibly by Alucard (though I doubt it). Yeah, she could be Alucard's long lost half-sister, not likely though. Then again, she could just be an artificial person created using magic to be a vessel that can absorb and use these possibly forbidden powers.
The truth is that we don't really know anything about the story of the game and we know next to nothing about the characters. I think the fact that we don't know much will make the game a lot more fun. Admit it! When CV games came out in the past, the ones that seemed to be the most fun were the ones we knew no much about or had a completely new and untested feature or game play. For example, SotN was the first true game that had certain elements of RPGs that have revolutionized the series and is the model for almost all the recent CV games. And that is what made SotN so fun.
OoE is going is somewhat new direction by merging the game layout of CV2 and SotN. I think the huge environment and new battle system, as well as a mysterious storyline, will make this game a huge success and worth waiting two more months, even though it is practically all I can think about. Konami should really release another official trailer to hold us over. At least I think so.