Multiple problems with "Override defaults with the following values" checkbox

The "Override defaults with the following values" checkbox has multiple problems:

• With the latest release of Nodewords module, it no longer renders at the top of the fieldset. The weight needs to be decreased.
• It generates a PHP notice: "Undefined property: stdClass::$nodewords_nodetype_override in nodewords_nodetype_form_alter()". A simple test for the presence of this property before using it fixes the problem.
• It contains a link to the content type edit page even if the active user doesn't have access to visit it. The text can be conditionally hyperlinked based on an access check.
• That link is confusingly worded, especially to end users who will have no knowledge of the name of the module supplying the functionality. I propose changing the text to something like "Override per content type default values with those filled below."

Patch to follow.