I read the end page first sometimes, or at least early on. I like a glimpse of where the story is going, but the ending lacks context, so I don't feel particularly spoiled. The fun for me is in seeing how the characters end up where they do.
I also re-read books despite knowing how everything ends. Do people who don't like spoilers not re-read books?
I almost never reread a fictional book no matter how much I enjoyed it. While I'm sure I'd get more out of a reread, I figure I'll get even more out of reading a new book. In other words, the marginal utility of a new book is greater than the marginal utility of rereading a book.