The only other one you missed was #4.
Buffy dies twice - once at the end of Season One, which causes Faith to be created as the new slayer, and once at the end of Season Five because it is the only way to send Glory back to the other dimension and save Dawn. This causes Willow to use Dark Magic for the first time to resurrect Buffy, which is something she becomes addicted to and, sadly, turns her evil when her girlfriend is killed by the Idiot Boys.
It could be argued that she dies three times, because in the Season Two episode where the vengeance demon creates an alternate reality where Buffy never came to Sunnydale, Buffy is lured to Sunnydale - where Xander and Willow are vampires and Willow stabs Buffy to death, but because that's an alternate universe I don't think it really counts.
Particularly since during the Musical Episode Buffy sings "I've died twice."