The OS most of us use ubuntu because its much easier/tested. But you can run on other things... even Windows. And you can also run everything under docker images, which the API node code is prepared for too.
Hardware, depends. But nothing short of 64GB just for the API node. 8 cores or more... of a recent CPU I would say is the minimum to start playing. And a good 4TB of NVMe storage (suggest more even for backups).
Didn't quite catch the "authenticate" part, can you rephrase that?
No worries about questions... Ask away!
