number of list items

This can be set in the Reading settings on your dashboard, or via an action hook, such as:

function my_set_posts_per_page($query) {
        if (isset($query->query_vars['listing_category])){
            $query->set('posts_per_page', 10); // set this to the desired number
        }
    }
    add_action('pre_get_posts', 'my_set_posts_per_page');

I’m adding this as a user setting to the next release, along with adding the appropriate navigation links to the category.php template (these are currently non-existent and have to be copied from your theme… that was an oversight on my part).