All of your insert bindings seem wrong on your confirm pages in your "store cart summary" and "store cart details" server behaviors.
You should probably delete that code if you don't need it. To get it working without the error you could just change:
$ConditionalQuery->bindColumn("OrderID", "d", "segufix_OrderID", "WA_DEFAULT");
to:
$ConditionalQuery->bindColumn("OrderID", "d", "". ($_SESSION["segufix_OrderID"]) ."", "WA_DEFAULT");
But you might as well delete that code chunk entirely since it doesn't seem to insert any relevant data.
I don't even see the email code on the page. Maybe you removed the email code when you thought you were removing the database insert code? The database insert code appears to be in place it is just inserting bad data.