Regarding the quote from Maleficent….the kiss breaking the curse and she got over it…..if you look at the fairy tail, Philip killed the dragon/Maleficent before awaking sleeping beauty. So the reference must be to something else. Taking into consideration Regina’s whole back-story of becoming evil because of love lost, I think this is what Maleficent meant.
Not sure about the whole amulet thing though. Couldn’t there be more than one? I think there’s a wrath tied to each amulet otherwise there would be wraths flying around all over the place, and giving the mark to someone awakens it to search for that soul.