Forwarding request headers as-is from Gateway to Listed Service


I am new to Gateway topic. I request you to let me know

a) if the Federated Gateway (Services publishing subgraphs to gateway) automatically forwards the request headers received from Client (for e.g. a web or mobile app) to the Listed Service ?

b) Similarly, when the listed service sends the response with custom http status headers, will gateway route them to client as-is ?

c) Is it a best practice to validate an authentication token in Gateway first before routing the request to requested service. ? If i use a Interceptor or a Middleware in NestJS will it work

please respond