The voiceover, with its mention of Barnabas bringing his curse into parallel time, suggested to me that the vampire curse - not Barnabas's specifically, but rather the general concept - started in one particular time band and was carried, like an infection, from band to band, until it had spread throughout all the time bands.
Barnabas treats Buffie similarly to how he treated Charity: as if she were something quite special, not a drink-and-discard doxy, while in the meantime the sweet young thing he's really yearning for is another Josette clone. It surprises me, because I wouldn't have thought Barnabas would see anything in Buffie beyond a quick fix.
I don't really enjoy what's going on right now, but I must admit there's interesting writing. Angelique is carefully balancing the suspicions that she's creating in Quentin and Maggie, so that neither one is willing to confront the other with them. And Cyrus is being pushed by random, unrelated occurrences to become John Yaeger again.