It is my understanding that the firewall IS included in Avast premium, therefore I cannot understand why, when configuring individual program rules, I keep on getting a message to the effect that it is a paid program, not included in Avast Premium.
It is included. A screenshot would be helpful.
Right click avast tray icon and select about to see what avast and build number you have
Avast repair >> https://www.avast.com/faq.php?article=AVKB204#artTitle
Remove or add component >> https://www.avast.com/faq.php?article=AVKB96#artTitle