Web Hook related questions

Hello community,

A few questions related to the Webhooks available in Postman:

  1. If I were to host a WebUI which is accessible anywhere from the Internet, and needs to trigger (to run) a collection, can the collection be in a private network? If so, how does the WebUI control who gets to trigger to run the collection? Is there a way to authenticate? (Maybe a combination of

  2. How do we pass values to environmental variables in a Postman from an external Web portal?

  3. How to return output of of Postman back into the Web portal.

Are there examples of above somewhere?