To answer your questions:
1. There is no difference between the hard and paperback versions (other than the obvious). The hardbacks are limited edition in that they are a limited print run that will not be repeated, so they are more collectible than the paperbacks. Really comes down to which format you prefer.
2. The maps are the same as those from the first edition, but obviously the
Act 3 map has the new locations marked for the bonus content.
3. Goldsboro were taking pre-orders of the book (with full sets of bookmarks with each pre-order). I believe they have sold out already (!) but I should be able to confirm later. Follow my twitter stream for updates on that (link on my Buy page. If they have sold out, my editor is going to see if they want more copies and bookmarks. Don't worry, plenty of bookmarks left so I'm sure you'll get some eventually!