Don't particularly like any of the titles in the original post (war of the wizards has some potential though... Now my take on these rumors (badly done, but eh.)
Book Rumours
...The Final Horcrux will kill Harry during its destruction as it is something very personnel to him - Maybe, but don't all the horcruxs need to be destroyed before Voldermort can be killed? Harry can't die before the final battle. During it maybe, or after, not before.
... An evil double agent will provide the final shocking twist to the story. rumors are suggesting that it could be McGonagal - That would be quite a twist, JK likes her double agents, what with Snape and all. An evil McGonagal? Scary.
... Ron and Hermione will finally become an Item. - I guess it's bound to happen, this romance has been building for six books (though I think Harry and Hermione would have been better, but eh)
... Harry WILL NOT return to hogwarts as a student - Maybe not, but I think a horcrux could be there, after all 2 horcruxs turned up in two of the places (or near by) that Dumbledore revealed to Harry (the cave and Marvolo's house), and hogwarts was special to Voldermort (though the diary was destroyed there, so maybe that counts...) Still, Harry needs teaching up if he is to fight Voldermort, and destroy Horcruxs, so maybe not as a normal student, but for training, or a showdown, I think it should happen.
... Dumbledore will return - In some form, I think that's a big possible.
... among the 4 deaths rumored to be taking place are Harry, Voldemort (obviously), Remus, Snape and Lucius - I'd be sad if Remus died (that's all of James Potter's group then, baring Wormtale, who I think will die, maybe some of the other prominant death eaters to), I think though that he will end up fighting that evil werewolf, the one that bites children, and he'll win! Die maybe, but still win. Snape will be vital somehow, though he and Harry could die. I could see the death of Lucius (if it occurs) somehow being pivotal to concluding the Draco story arch (maybe he tries to save Draco or something from Voldermort, or Voldermort kills him out of malice, either way sending Draco to the good side)
... the location of the Finale battle have differed some suggesting the great hall at hogwarts. - This I can really see, seems symbolic really, Hogwarts, perhaps the most important place in shaping the young lives of both Tom Riddle and Harry - a great place for it to occur, to end where it all began.
...there WILL be a wedding - Bill and Fleur, hopefully Remus and Tonks as well. I'd love to see something really happy happen for Hagrid, maybe him and Madame Maxime?
...Lily Potter will return with information that will help harry uncover the location of the Final Horcrux - During the battle in the grave yard Harry was in a fashion helped by his parents, I guess something might happen...