I read that and the Twilight books as part of my "studies" as a college professor in an attempt to stay in touch with what the youth reads. The writing (in both, mind you) was so pathetically awful that I briefly lost all faith in the coming generation. Then my students agreed it was bad, and I felt better about the future. Also, having read Twilight, I understand the crossover between fans; they're both simply dreadful, in mechanic construction, plot, and characterization that if you're a fan of crap, you'll be a fan of both.
As far as Harry's staff, he mentions that he and Ebenezer's are from a lightning-struck oak. Eb specifically mentions giving him another "blank" from that tree, so I'm assuming all of Harry's staves are made from that same tree. It's odd, because most trees are killed when struck by lightning; they explode, or they're injured so severely that they die (but will survive for a while). If the outside of the tree is soaked from the rain, it's possible that the lightning flashes over it, which could char the outside.
Regardless, lightning-struck trees are generally regarded as weaker than ones that are not. If it is stronger than standard oak, it must be as a result of magic channeled through it. Harry's got big hands, and he mentions being able to wrap his whole hand around it. Judging from a height of 6'9" (which I've seen here) that would give it a circumference no greater than 8.91 inches. That puts its diameter somewhere around 2.8 inches or less, unless I've forgotten what math is. I'd figure it's about two and a half inches across. For reference, regulation baseball bats are no greater than 2.61 inches across at its thickest.
Anyway, that's a whole lot of wood. Wouldn't weigh much either; American Red Oak is dense, but not that dense. Probably somewhere around ten pounds if it's six feet long. But yeah, it's got heft.
Meanwhile, his blasting rod is frequently stated to be as thick as his thumb, so it's pretty narrow. I always thought of it as more of a magic wand that he called a rod because it sounded more buff.