I loved reading your comments, Mare! I'm glad you finished the series and enjoyed the last three books especially! I like the later books better too, as a whole - my favorite is Deathly Hallows, followed by Goblet of Fire and Half-Blood Prince. They're much deeper and darker and complex than the first two books.
I think they're definitely worth reading again - you pick up a lot when you reread. I love how JKR planted bits of information that would be important later in the series in the early books - seemingly minute details became vital information later on! She's brilliant.
Your comments about the deaths were interesting because my reaction was completely different LOL. The first time I read DH, I absolutely BAWLED over Hedwig's death. It doesn't make me cry like that anymore, but the first time through, that was the worst one for me, crazy as it sounds! Dobby's death does still make me cry. I guess it's the deaths of those who were most loyal to Harry and most innocent hit me the worst. By the time it gets to the Battle of Hogwarts, you get to where you just expect the deaths, so maybe that's why those don't get to me as much, even though I love the characters of Fred, Lupin, etc. I don't think any of those deaths were pointless - I think she needed to kill some big characters in order to show the real danger of what they were facing; it would have been unrealistic for everyone Harry was close to to survive. Tonks and Lupin both dying, leaving their baby an orphan, paralleled what happened to Harry's parents, so I thought it was fitting - and I'm not sure it ever says, but I always assumed that Tonks's mother raised the baby, Teddy, because from the epilogue it sounds like Harry and Ginny didn't. As for Colin, I think he was put in as just another innocent figure in the long line of those who died trying to protect Harry: his parents, Sirius, Dobby, etc. The fact that he's mentioned as Harry is leaving the castle to go into the forest and surrender himself to Voldemort is significant - I think it's what helps give him the strength to do it, seeing yet another dead body of someone who was fighting for him, who had no business being there, and knowing that he's the only one who can stop it.
I'm super excited they're making this one into two movies - I think if they didn't, it would be too rushed and not nearly as powerful as it should be. From what I've heard, it sounds like they're splitting the movies around the Malfoy Manor chapter, where the trio gets captured by the Snatchers and taken to the Malfoys'. That will take them far enough to introduce the Deathly Hallows in the first movie (and I think there will be plenty of action between them going on the run, sneaking into the Ministry to get the locket, Godrick's Hollow, the silver doe, the scene at the Lovegoods', etc.) and leave most of the second movie to be dedicated to the action at Hogwarts, which means it should be awesome! Sometimes the climactic parts of the movies are rushed, so that shouldn't happen this time around. I'm sure they'll include Dobby and Neville and everything because those parts are so important. I know they're having the wedding in there too, so Bill at least should be in it, and Fleur will be back too. I can't wait!