You can alter the gallery shortcode. See this. Look through /wp-includes/media.php til you find add_shortcode('gallery', 'gallery_shortcode'). Add this to functions file, rename ‘gallery_shortcode’, and add your new options to the $atts = shortcode_atts( … array. Then, add how to display those the the output.
Then add:
remove_shortcode('gallery', 'gallery_shortcode');
add_shortcode('gallery', 'gallery_shortcode_yournewname');
