For the record, I'm a 31 year old male history graduate. I think the problem is that you've approached the show expecting it to be something it isn't. The series is deliberately a metaphor from the trials of young adulthood. The 'monsters' themselves are repetitive of this. The show's strength was that it could have had a satisfying episode without having to have any 'monsters' in it at all. If you were looking for a show which is "hero slays vampires" every week, with no levels of characterisation or coherent plotlines, I'd suggest you check out "Blade: The series" - currently showing on Spike TV in America. Although I'd grab it whilst you can - I'd expect something that vapid to be canned pretty soon.
No, I fear it is you that does not understand vampire "lore" - as you seem to have missed the fact that the vampire has historically been a metaphor for the generation in which it was written - a reflection of that society rather than any kind of "rules" as to what a vampire is. In fact, if you look at historical folklore of vampirism, the Eastern European stories tell of people coming back form the grave and doing things like... mending shoes... and housework. Hardly the stuff created by Polidori and Stoker.
In Stoker's vampire (and I assume that is where you draw your idea of what a "lore" is) Dracula is the metaphorical representation of fading aristocracy in the late 19th century Europe. By that definition, he is able to forward his "bloodline" without the messing about with relationships and sex and the suchlike (the vampire had not be sexualised in literature by this point). The word "blood" is used much more figuratively to represent lineage than literally to refer to actual blood in the story. By the same token, Salem's Lot represents the McCarthyite "enemy within" mentality - with implications of America during that period reflected in King's work - the cold war having a very direct effect upon the perception of "horror". This doesn't (to me) seem to be effectively reflected in the movie version.
By that same token Buffy continues that tradition - in the late 90s i swas reflecting a listlessness of the "Generation X" mentality. In this interpretation, the enemy is the "inner demons" and a such this is represented in the show effectively. Not least of which with the usage of grey-areas - where evil is not as black and white as we once thought. All very post cold war and post-modern.
Not at all . I would posit that you know rather little about "myths" of vampirism - as the modern interpretation (as used in Hammer movies, Salem's Lot, Buffy et al) were invented by Polidori and Stoker. Historical "myth" about vampirism bares little to no resemblance to this. Vampires, as we know them in modern culture, are a literary tradition - not a folklore one. As such, Buffy follow that lineage more than adequately.