ADFS configuration in CRM 2016

I have DEV and PROD server. I would need to configure ADFS in CRM.

Environment setup:

• Active Directory -separate server
• ADFS- separate server
• DEV-separate server
• PROD-serparate server

I would need answer for the below question.

1. What is the purpose of ADFS configuration in CRM?
2. Shall I use single ADFS server to configure both DEV and PROD CRM 2016?
3. How should I configure ADFS server for CRM 2016?
4. To enable ADFS do my CRM need to expose public?