phranque - 7:24 pm on Mar 2, 2013 (gmt 0)
you can specify all 5 nameservers (2 NHC & 3 dnsever) at your registrar if you like.
it will give you "extra redundancy".
those (5) IP addresses are the addresses of the nameservers, not your web server, so they should be specified along with the nameserver hostnames in your registrar config.
the zone file at each nameserver needs to know about all 5 nameservers.
i would assume you should have a simple interface at dnsever to edit the zone file and hopefully your NHC nameserver also gives you this flexibility.
one of the nameservers will have to be the master - probably one of the NHC nameservers.
the A records should point to the IP address of your web server, assuming you have a static IP address.
if the NHC is assigning the IP dynamically then you will need to use the dynamic dns service at dnsever.