Try reading them adult books (if you're not already—and especially classics, they tend to have really nice prose that you want to run your eyes over several times just for the sensation, anyway) or classics of children's literature (e.g. The Jungle Book). Might help. Lots of childrens' books are just plain bad.
Yes. The emphasis carries a lot of information in addition to the simple text. I find it hard to do when reading aloud from a book I haven't myself read before. In fact I think it's one reason I tend to pick my personal childhood favourites to read.
Perhaps this is lazy. I wonder if other parents do the same?
[EDIT] I've read my kids a couple old favorites, though not ones I've read recently. In part I've used them as an excuse to get through entries my personal to-read list, in fact. Multitasking! Especially when they're really young, they don't know the difference. My 4-year-old's super into Ovid right now, which is awesome. Have to skip the too-sexy or ultra-violent (or, uh, both) bits, but it's working alright.