Protection level when using SNC Client Encryption

Hello,

I have a two questions.

1. When using SNC Client Encryption to secure communication between SAP GUI and SAP Server, is it still possible to choose between one of the three SNC protection levels (authentication only, integrity or privacy)? Or is full encryption of the communication between SAP GUI and Server the only option?
2. What does SNC protection level "authentication only" exactly mean? Depending on who I talk to I receive a different response and the documentation is quite cryptic.  Does it mean that the endpoints of the communication channel (SAP GUI and Server) mutually authenticate (via certificates?) or does it mean that in the communication flow between SAP GUI and Server only the user ID and password are encrypted and the rest is in clear?

Thanks in advance,

Frank.