Reordenar o adicional tooltip a campos del billing address
http://inchoo.net/magento-2/frontend/reorder-input-fields-shipping-billing-step-magento-2/
Dentro del di.xml crear un plugin como este
<type name="\Magento\Checkout\Block\Checkout\LayoutProcessor">
<plugin name="checckout-billing-fields-personalize" type="\Daytours\Checkout\Plugin\Block\Checkout\LayoutProcessor" sortOrder="1" />
</type>
Para el observer
// $jsLayoutResult['components']['checkout']['children']['steps']['children']
// ['billing-step']['children']['payment']['children']
// ['payments-list']['children']['checkmo-form']['children']
// ['form-fields']['children']['postcode']['sortOrder'] = 71;
// $jsLayoutResult['components']['checkout']['children']['steps']['children']
// ['billing-step']['children']['payment']['children']
// ['payments-list']['children']['checkmo-form']['children']
// ['form-fields']['children']['country_id']['sortOrder'] = 0;
$jsLayoutResult['components']['checkout']['children']['steps']['children']
['billing-step']['children']['payment']['children']
['payments-list']['children']['checkmo-form']['children']
['form-fields']['children']['country_id']['tooltip']['description'] = 'asdasdadads ad dad as';