Wordpress : All pages 404 except homepage after Migration

In the httpd Conf for the same website change

AllowOverride None

to

AllowOverride All

As per my understanding it will make the .htaccess take effect.

Wordpress : Mixed Content Warnings with HTTPS

If want to make sure that your server/website is ready to handle HTTPS traffic. You can do this via your /wp-config.php file.

/* Handle HTTPS Protocol */
if ($_SERVER['HTTP_X_FORWARDED_PROTO'] == 'https')
  $_SERVER['HTTPS']='on';

This will make it so that your website/server accepts all HTTPS requests, and also enables HTTPS