Hi,
The "order_shipping_method" is the plugin name and the "order_shipping_id" is the ID in the hikashop shipping table.
If you want the final name, you have to load the configuration for this specific shipping_id and read the column "shipping_name".
For the header of the table, you can just use a classical column without sorting.
<th class="hikashop_order_customer_title title"><?php echo JText::_('CUSTOMER'); ?></th>
You have to create the cell in the body of the table too with this time the code given by Nicolas.
Regards,