By default the index.html file will be the one requested for. If you want to see the directory listing you would have to change the rw permissions on the directory to be public.

It's up to the website what to show you when your request is for a / resource. Most servers show a default page. Directory browsing is not desired by most sites and you often see an error message if there is not a default page. You cannot change this from Firefox.

Is that your phone number? You may want to edit that out of your question.