What should the community-name be in the URL call?

Hey Community Members, perhaps you can help me with something.

The thought process here is that I am currently building an app that will take a spread sheet of email address, find their userid by searching the community for the email address, using the http://community.lithium.com/community-name/restapi/vc/users/email/[email] api and then adding the role using the role update api. (I have a separate file that links @company.com emails to the roleIDs) The documentation seems to indicate I need to authenticate before I start making these calls but I'm not seeing documentation regarding header information or anything else that might indicate where to put the auth key. 

1) Do I need to authenticate before calling those API's 

2) Is there an easy place to find that community-name, is it the ID or the text name? What exactly is the api expecting here. The example provided doesn't change community-name in the example for email look up but I am not able to apply the same in my community. 

Happy to share the job when it's finished as I suspect many others are getting tired of manually updating roles, just need help understanding the API a little more. 

Let me know,

Nick