Hi & welcome.

Nothing is necessary other than Comodo Firewall Pro if you ask me, but it is recommended to use antivirus as well. It's true that there are shared functions, but not much. Both CFP and CAVS has HIPS; disable the one in CAVS and use CFP's Defense+ instead.
The antimalware BOClean is a complement to CAVS, with malware signatures that I don't think CAVS has.
Memory Firewall does something that none of the others does.
At this point, all these four programs actually do different things, so better run them all! (just remember CAVS is still in beta).
LA