Thank you for the detailed info.

I just found this package for doing API calls using PHP

https://github.com/RikudouSage/LemmyApi

Is there something simular to this for NodeJS also?

it meant the communities INSIDE the instance would not transmit out… but the rest would work as normal.

Lets say you have a private federated instance named salk.world. salk.world users can access, post and comment on other instances like lemmy.world but other instances and users cannot view content on salk.world?

Before when you can check off federation and private instance, you could not view the instance unless you were logged in but could you view the instance from another instance being logged into another instance or no being logged into another instance?

Or does it only federate in a way were users inside the private instance can access the fediverse but the fediverse cannot access the private instance?

By leaving the federation box unchecked and having the private box checked off, will the instance not be visible to the public unless your logged in?