When I tested this out I was not able to login with the user I registered. Based on what you have here if you have the remember me checkbox checked it should store the username in a cookie. The username field should have it's value set to this cookie if the cookie is set.
The auto login cookies should only be used by the auto login User Authentication server behavior.
If you have already populated the other cookies you will need to clear out your cookies, at least for this site, to see how they are working by default.
If your password is being prepopulated this is probably due to a browser setting.
