I updated the trigger for your paypal code so that it won't submit when other buttons are clicked.
The eCart checkout skips the confirm message when no shipping charges are changed. If you want that you would have to add the confirm page content to the pp_confirm.php page including a submit button and form with a blank action. Then update the trigger for the Process Transaction server behavior to use the button click event instead of the "Before Page Load" trigger it uses by default.