how to load the comment template from a plugin

You can use the comments_template filter to alter which file your CPT will use for comments.

function wpse_plugin_comment_template( $comment_template ) {
     global $post;
     if ( !( is_singular() && ( have_comments() || 'open' == $post->comment_status ) ) ) {
        // leave the standard comments template for standard post types
        return;
     }
     if($post->post_type == 'business'){ // assuming there is a post type called business
        // This is where you would use your commentsnew.php, or review.php
        return dirname(__FILE__) . '/review.php';
     }
}
// throw this into your plugin or your functions.php file to define the custom comments template.
add_filter( "comments_template", "wpse_plugin_comment_template" );