Check the quest item section of your inventory for books (IIRC it is there rather than the miscellaneous section). The guy you rescue mentions the book in the dialog, and it goes directly into your inventory.
If you edit your post, there is a 'Delete Post' button beside the 'Change Post' and preview buttons. There is a two day time limit on editing posts, though editing a post will not flag the topic as updated, so people may not notice it.
