I went ahead and started over again. I cleared out all the files I believe were going to be replaced and ran the Checkout Wizard again.
It did not install the UE behavior.
After completing a purchase, a gray screen was returned by the PayPal frame after a payment instead of forwarding to checkout_successful.php
I assume, I need to add the UE Behavior to the checkout_successful.php page. Should I also check the box to manage email from the file webassist/email/templates/wa_receipt.php? Will this resolve the problems?
(Please note the UE behavior DID NOT install using the Checkout Wizard for future releases of eCart )