I was considering using the VPN service PIA. Are there any settings within Comodo Firewall that need to be altered/corrected in order achieve compatibility? Also, is the Comodo Firewall download link still valid or should I be using CIS instead? There are two separate links for each (free) download.
Usually if the VPN service you plan to use is signed by a Trusted Vendor, there will be no settings to be changed either in Comodo Firewall or CIS.
You can pick the Offline installer for CIS Premium and untick the AV component during install, this will install Comodo Firewall.