Results of these predictions.
Dudley and Petunia Dursley
Nope. I was disappointed we never really found out much about Petunia and Dumbledore's relationship. We did get some insight into her relationship to her sister, via Snape's flashback. But I was hoping for more resolution there when the story just didn't head in that direction.
Grawp will take action
I think this was borne out of a hope that this character had some greater purpose. Nope. I just am not that interested in him and he got a whole lot of pages in books five and six. Sigh.
Dumbledore dies and returns in a different form to guide Harry
I figured that he'd provide helpful advice at an unexpected moment. In fact, Harry and friends spent the first half of the book hoping this would happen but it didn't. (I guessed that the eye wasn't his, since it was always described so fleetingly. And I correctly guessed, after a bit of thought, who'd summoned the doe.) He did get to speak to Dumbledore in a different form at the end to offer some final words to Harry. So... sorta?
"Harry will kill Voldemort. Snape, having evaded Harry, will be there to help at the critical moment and finally prove that he is on the side of good. I think he killed Dumbledore on his orders and will use this to get as close as possible to Voldemort. Harry will think he's fighting both of them."
Called it! Not too challenging, but I managed to get that all right. Where I was off is that I expected Snape to act at the end, when he was in mortal peril. He did (by helping Harry) but I thought it'd be a strike to weaken Voldemort.
"Harry discovers that he is one of the unknown Horcruxes used by Voldemort. He kills himself at the same time that he kills Voldemort."
Called it! Rather, Kit and I did. This was something we tossed around after book six. I really loved it* but I didn't think Rowling would make that brave choice because I didn't think she wanted to kill Harry. But she came up with a way to make it work. Yay! :)
*I'm a sucker for ying-yang morality and "kill the evil within" themes.