this is not the way the wizard would write the code.
for 1, the store order summary behaivor would be on the confirm page not the cart page.
for 2, the code for each column uses a ternary expressionthe format should be:
isset(session)?session:""
in other words, check if the session is set, if it is, use the session value, if not, use a blank string,
so:
(isset($_SESSION['eCartCheckoutForm_shipping_firstname'])?$_SESSION['eCartCheckoutForm_shipping_firstname']:$_SESSION['eCartCheckoutForm_firstname'])
should be:
(isset($_SESSION['eCartCheckoutForm_shipping_firstname'])?$_SESSION['eCartCheckoutForm_shipping_firstname']:"")
break that down to:
Question: (isset($_SESSION['eCartCheckoutForm_shipping_firstname'])?
If True: $_SESSION['eCartCheckoutForm_shipping_firstname']
if False: ""
thus preventing the undefined index error.