Steam SDK doesn't need stream?

The features that come with the steam works SDK seem really cool, but I am a bit confused on the requirements to use it. I imagine that they aren’t just letting everybody use there services, but I also see that they let people use it without even being on steam (Steamworks - Valve Developer Community ) and do not need to be greenlit (,_Using_the_Steam_SDK_During_Development ). So can I go and grab it right now and start testing it out right now? Are you just allowed to have the code setup but not run until you actually are greenlit?

Presumably, it lets devs test their software, once they have integrated Steamworks, without having to have released the game first!

Steamworks can be used for your games without being greenlit to test it. But that means that you have to use the App ID 480.
Normaly a Steamgame gets its own AppID. Without this AppID and without being greenlit you can only use the Achievements etc
that SpaceWar (the game of the AppID 480) gives you.

If you implemented everything correctly, then you can later add new Achievements etc on your own App Page (you will get one
once you are greenlit and in contract i guess). You will also get your own AppID.

But implementing Steamworks should only be down after you are ready with your Game and after it is nearly greenlit.

The UE4 Networks System works without Steam. So you can create the Server etc, make the Host/Join, Server Travel Function etc.
and in the End just enable Steamworks. Because the Network System is just some kind of wrapper.