New question about the IP

[Arcam]

I think it's better to change the dns template files rather than the ispcp core functions.

As to your second question, I don't really understand what you mean.
The primary and secondary name servers can be set during the installation, and if you want to use more servers, you can always change the templates.

But, as with any other changes, don't forget to write them down for any future upgrade/reinstallation.