Unity Build Server Technical Specifics

I can't find one place that has a deep technical breakdown of how the new(ish) Build Server licensing works. Here's what I understand from various sources - can anyone weigh in on whether this is all correct?

• Build server lets you use floating licenses instead of node-locked licenses
  • To use these licenses, you no longer pass username / serial information via the command line when starting the Unity editor batch process. Instead, you have a local config file. License management is automatic - it checks out a license when starting the editor, and returns it when the editor shuts down or crashes.
• Build server adds a restriction that you're only running the licenses in batch mode. No other restrictions are placed on what you can do in the Unity editor.
• Build server allows you to set up a license server within your local VPC/subnet that your Unity instances can talk to for licensing. This allows us to, for instance, spin up Docker containers, run batch commands and shut down the docker containers when finished, all seamlessly and without specialized code to manage licensing.
  • If you don't have any licenses available on the local licensing server, any Unity instances you attempt to spin up will fail immediately, rather than waiting for a license to become available.
• Build server is an addon to your Unity license. A base Unity Pro license allows you to run 2 instances simultaneously; each Build server license you purchase adds 3 more simultaneous instances on top of this.

Is all of this information correct?

We're looking to set up on-demand batch Unity instances for various processing tasks (for instance, spinning up a Docker container via a Lambda on AWS when we have a new model to process into an asset bundle) - anything else I should know before we go down this path?

Here are my sources:
https://blogs.unity3d.com/2020/09/25/offload-project-builds-with-unity-build-server/
https://docs.unity3d.com/Manual/ActivationFAQ.html
https://forum.unity.com/threads/unity-build-license-not-build-server-information.943550/