I am about to register a domain name and would like to know whether it is true that if you register a domain like mysite.co.nz for people who search my site in New Zealand mysite.co.nz will be one of the top results without much SEO? and als if mysite.co.nz is taken would it be worth purchasing my-site.co.nz?
It will take a strong link strategy to rank highly, and that required planned seo strategies as well ... you will probably rank in the New Zealand search pretty easily though.
Not really, but don't overdo the hyphen thing, one is enough. Also, if the non-hyphened one is available then you better go for it, if not then you can use the hyphened one, not a problem.