Nothing of value really to post but that's one point of blogging right? Some kind of quasi-Beckett nothing to say but will say it anyway attitude.
So - book forewards. My simple rule is never read them in advance for fiction but usually for non-fiction. And the simple reason for the simple rule is the foreward potentially ruining the story. A good example is Pankaj Mishra's foreward to Farrell's The Siege of Krishnapur (a fantastic and highly recommended book by the way). Mishra blithely reveals the ending of the novel and in a good bit of detail. That may or may not matter in some cases (today most people who read The Murder of Roger Ackroyd know beforehand the identity of the killer) but this is one novel where the resolution is not only in some doubt up to almost the end but has a haunting and effective coda that Mishra also reveals.
It doesn't help that Mishra's foreward is mostly pointless anyway. The only thing of real value is to place Farrell's book in the context of an entire subgenre of Mutiny novels that few Americans like myself, even the Anglophilic ones, are likely to know existed. (Actually I'd guess few Brits do nowadays either.) I also think of Ray Bradbury's foreward to the NYRB collection of John Collier's stories that while a nice little memory of Collier says almost nothing about this mostly forgotten writer. That book could have used a page of biography much like you get with a Penguin Classic. In fact Collier sounds like a full biography would be worthwhile. (And another by the way but those Collier stories are amazing - superficially little twist-ending pieces but greatly imaginative and surprisingly resonant.)
So why couldn't the foreward have become an afterward? In fact why aren't most forewards to novels/short story collections moved to the end? I'd guess it's partly tradition and probably even more marketing. The foreward's author is usually an additional selling point such as Bradbury with the Collier. I'm not really knocking the marketing - NYRB for instance frequently matches an appropriate foreward writer with each book.