1) The HemogenixCart_OrderID session is created by the store order summary behavior. The universal Email code must come after the store order summary code.
if you get headers already sent errors it is likely because of blank lines left between the php code blocks.
see the following post on the headers already sent error:
showthread.php?t=19285
2) in the waue_confirm_1.php page, this code:
if(!session_id()) session_start();
echo $_SESSION['HemogenixCart_OrderID'];
$MailBody = $MailBody . "\r\n";
should be:
if(!session_id()) session_start();
$MailBody = $MailBody . ((isset($_SESSION["HemogenixCart_OrderID"]))?$_SESSION["HemogenixCart_OrderID"]:"");
$MailBody = $MailBody . "\r\n";