Amaaaaazing start to a story i can't wait to read! Such an interesting premise; I like :]

This could be fun, and is a neat way of reconciling the two very different 'verses. Hopefully the potentials are still all 'activated'. A slayer apparently has the powers/ability of a human servant with all the marks --strength, healing etc-kind of like a living vampire in a way. Disadvantages-- they can't just kill any vamp they meet...legal problems, in the US anyway.
** What about Angel & his group in LA? Presumably he's the "Master of the City" there? Does he or Spike (if returned) have an animal to call? Human servants? ( I could see the members of the fang gang being Angel's human servants, it'd explain how they've survived so much).
This is going to be especially hard on Willow and Xander-they were BORN in Sunnydale and have spent their whole lives there. They don't have any memories of the real world to get back! Same for Dawn in a weird way, she was created in Sunnydale --would her fake out of SD memories change?

Nice start. It's hard to mesh the two worlds it looks good so far.

Awesome beginning! I can't wait to read what happens next! Thanks for writing!!