Where does the hangout hold? If on the discord server, which channel?

There is a #voice-chat-channel in the BDC server. And the hangout usually starts every Friday at UTC+6.

And question, how do writings from certain authors get added here?

This is a magazine from the community that gets published every week. For that, you need to get introduced to us at the server and the officials would decide the rest. Well, hope to see you there.