Thank you. That is exactly what I needed. I had found the content.404.php in my backup file (by doing a file search for 404), but not being a script programmer I didn't really know what to do with it. Knowing that it points to variables in the language files and that the language files were atleast partially editable in the cart script was just what I needed to know. I know have a much more suitable 404 error page.
Now to see if I can do something with the no shipping option output. I want to include a note that International sales will have to be processed manually.