the world pay email receipts cannot be modified, they are generated by the world pay service and world pay does not offer a way to add additional information to them. this is a limitation to the world pay service.
The order information should store in the database regardless of it being a test transaction or live. on the confirm page, the store order details and store order summary behaviors should have the trigger set to any form post so that the order can be stored when the checkout page posts to the confirm page.