I will try to reinstall the WAP with Powershell command. Yes, I have one static public ip only.
If the circumstances allow, you could also use the WAP as a reverse proxy for the other applications that also use port 443
If I am using a SaaS service from 3rd party, can the user to be authenticated through the WAP? Or it must be done on ADFS directly.
The WAP operats as Reverse Proxy (AD FS Proxy) for the AD FS Serivce. The behavior is like design. You have to configure the SAML/WS-Fed IdP, etc... on the adfs servers.
If I run a 2nd ADFS server on DMZ, what is the pro and con?
I do not understand...What do you want to achieve with it?