I think there's some misinformation here in regard to vampire perks. Someone correct me if I am wrong since my game is heavily modded, but while your vampire does lose the perks if they are cured, they DO get back the spent perk points if they are turned again. You could easily just re-purchase all of the perks you lost once you turn back.
@Simmerville
I don't know the answer to your first question since I usually make my Sims drink from other Sims, but your second question, I think is yes. Mortal Sims, for me at least, have appeared in Forgotten Hollow multiple times.