By default, eCart displays the shipping address on the confirm page. If you wanted to display the billing information you can get that information by opening the Bindings Panel in Dreamweaver and expanding the Payer Profile from PayPal Express Checkout.
You can then drag the information you need to the page.
In regard to changing the address, if the user changes their address on PayPal then the new shipping address is returned and displayed by default on the eCart confirm page.
Let me know if you have any other questions.