Various bits of PHP / HTML to customize this theme. PHP can generally be added to the custom.php file included with the skin.

HTML

PHP

1. Add text to the top of the shop page

function wc_custom_shop_desc() {
    if ( is_shop() ) {
        echo "My custom text";
    }
}

add_action( 'woocommerce_before_shop_loop', 'wc_custom_shop_desc' );

FAQ

1. How do I change the number of products on the shop page
Download the the WooCommerce Product Archive Customiser plugin and then you can find the option under WooCommerce -> Settings -> Products -> Display: Products per page