Now that you have read the first three links, The first Restoration link I suggest you check out is Vikki's excellent tutorial on Layer Masks on the RetouchPRO forum. It shows an extremely easy way to clean those annoying marks and spots without using the clone stamp tool. http://retouchpro.com/tutorials/?m=show&id=63
Here's a link with instructions on a way to use layer masks in Elements. It works! Not anymore http://www.photofocus.com/showarchive.php?aid=153&cid=3