What is OOTP please?
Arrrgh!!!!
Did you have to say that? Now I am gonna have to dig out OOTP and look myself.
My theory on why Snape didn't kill Harry after killing DD (and this is long, so please forgive me):
Many people I have talked to think DD was pleading for his life, when Harry heard, "Please, Snape". I think it's the opposite. DD was pleading with Snape to take his life.
DD has always trusted Snape, and he knew that he would have to beg Snape to get him to kill him. I think DD trusted Snape so much that he would trust him to take his life. DD knew he had to die in order for Harry to finally take on Voldemort (sort of Obi Wan-insh). I think he also didn't want Draco to do it because he knew that if Draco killed him, there would be no way for Draco to ever come back and turn away from Voldemort.
i think that it might not be at grimmald place because remember when mundungas got caught stealing from sirius's house by harry, what if he stole the locket?