I have followed your instructions but still receive errors !!
Still the same issue with eWay payment gateway advising that it's an incorrect value.
Using PayPal now partially works. The correct amount including shipping is displayed on the PayPal site but when the transaction is process only the product amount is charged and the shipping is not included. Details are written to the database and a conformation email is now being now sent. Client is successfully redirected to the checkout_success.php page.