HTTPS to HTTP rewrite rules not working as expected

The SSL admin and login redirection should be done through the FORCE_SSL_ADMIN constant in wp-config.php:

 define('FORCE_SSL_ADMIN', true);

For further information: Administration Over SSL

Aditionally, if you want be redirected to http when you’re logged and in the frontend, take a look at:

Redirect WordPress front end https URLs to http without a plugin