You could shorten the urls a bit by putting the forum in the root folder, no major reason not too except for organization purposes. Other than that, doing what you are requesting really won't affect SE results that much, and may require some significant changes to the files in threads - Rick or SD might know a shortcut, but I think changing how the forum uses URL's will affect all links within the forum, including the index, each forum, links to new posts, replies, everything will need to be updated.
