Yes that is right.
and the external IP address of your nameserver (for example your static IP)
People have different setups. I have only a single static IP at the moment so both of my nameservers are on the same IP.
For ns2 you should have a second IP but people rarely complain about that these days due the world running out of IPv4 IP's ...
Remember that if your server goes down then both of your name servers go down.
Did you take a look at Falkos new how to about setting up DNS ?