I would definately change that "suggested" path. While it will work initially, the ".wagner" part of the URL is a Dreamhost "dataglob" that is subject to change at Dreamhost's discretion.
Should that change, you Wordpress will break. Instead of using the suggested "/home/.wagnall/user/mydomain.net/wpdir/wp-content", change it to "/home/user/mydomain.net/wpdir/wp-content" and it will still work, and will not break if Dreamhost reconfigures. Of course, you can use a different directory if you choose to do so.
Either way, I would remove the "dataglob" from the path.