Few Questions on Microgateway OAuth implementation

[#1]

Hi Team,

I have few questions regarding OAuth implementation in Microgateway:

1) How does OAuth works internally in edgemicro? Does it make a call to apigee edge when generating token using CLI??

2) Is generation of token through CLI is different from that using API call??
3) For validation of OAuth token does it go to Apigee edge or it validates within the microgateway??

4) Can we set the expiry time for OAuth token in microgateway?

5) What is best practice to secure our internal APIs using microgateway?? Shall we use both API key validation and OAuth or either will do?? Because as per docs it says that for securing your APIs either use API key validation or OAuth.

Thanks.