In most cases you should get name service from your Web host. What to tell your registrar When you register a second level domain name, the registrar will ask you what name servers to use . If your Web pages will be here, you should use mine. Then I will be able to create third level domain names for you easily. If you can't receive mail at your contact address, you lose control of your domain.
Servers come and go.
IP numbers change. You have to be able to change your DN server info. If you can't, and your DN servers move, your domain stops working. For your registrant address, use your group's post office box if you're sure it won't change for years to come. Otherwise choose a reliable person in your group and give her or his street address.