How can I sort posts by the date and a custom meta field?

Basically, I am reading right out of the Codex page for WP_Query.

You want a meta_query similar to this with an orderby parameter with the two values you want to order by. The first is dominant.

$args = array(
    'post_type' => 'post',
    'meta_query' => array(
        array(
            'key' => 'rating',
            'value' => 3,
            'compare' => '>'
        )
    ),
    'orderby' => 'rating post_date',
    'order' => 'DESC'
);
$query = new WP_Query( $args );

I don’t know what your rating field is named and I don’t have your posts and your ratings on my system so I can’t test that. Hopefully that will get you started.