on the confirm page, in the store order details behavior, you have the DetailOrderId column bound to the OrderID session. but the session being created by the store order summary is named WA_Store_Cart_OrderID
you need to bind the Details OrderID column to the correct session, WA_Store_Cart_OrderID
the two form buttons are correct, the CheckoutWizard_submit button is the checkout form on the checkout page.
the Payment_submit button is the final submit button that processes the transaction on the confirm page.
to debug the AJAX issue, Ill need a link where i can see the problem and details on how to reproduce.