This is kind of a dumb question, but do I need ISPconfig running for my websites to function fully? I was thinking for security reasons of stopping the ispconfig service and only running it when I want to make changes. Thoughts? Thanks.
You can stop ISPConfig without affecting your websites. But webmail and phpmyadmin on port 81 wil then be inaccessible too.
Or you put them on your "normal" webserver... another thing, maybe easier, is just to disable access on port 81 or NAT it to 80 via iptables