[Plugin: Better WP Security] About renamed wp-content folder

If you have no content yet it can only interfere with some plugins that hard-code it in. Usually even that however can be overcome by pointing the problem out to the plugin developer who can make the link dynamic. If you already have content with media (images/etc) changing wp-content will break the links to that content

As for ServerSignature, turning it off will not only not affect it but should be done.