1. When did you input www and IP address? Was it when you installed ISPConfig or when you installed server (OS)?
If it was when you installed ISPConfig - to fix your domain go to => Management => Server => Settings => and change your domain name and IP address if needed. I ma afraid that you will have to fix your websites settings afterwards.
2. About pri.0.168.192.in-addr.arpa:
do you want to run your own DNS server? In this case look here
and here for more info
. Basicaly you will need to change your internal IP to external IP for DNS settings. (do not mix it with website settings - see bellow!)
When I add a domain in ispconfig, it automatically uses my local ip address.
If you want your websites to be accessible, they have to use internal IP addresses in ISP manager => New website menu. If you use external IP for them, your visitors will land on Shared page warning asking them to insert name and not IP address even if they used name.
I am newbie too but this I already discovered. Hope it will help.