Hello Agbams,
after a test of my site speed on gtmetrix, I got some issues with configure entity tags; 'there are X components with misconfigured ETags'.
This possibly has to be resolved at the webserver level (virtual host configuration or possibly .htaccess).
1. Does this pluging works with wp super cache?
I'm afraid no.
WP-Super-Cache creates static versions of the content, which are served by the web server. In that case the web server is responsible for all HTTP response headers.
Add-Headers adds headers to dynamically created content.
2. Will it solve my gtmetrix issues with etags misconfiguration?
Yes, if WP-Super-Cache is not used. But, as I've written above, this issue can be resolved in the web server configuration or htaccess file.
Hope this helps.
Kind Regards,
George