There's not much that's new in this build. Things that we've seen previously are some changes to Fluent Design, which added an effect to AcrylicBrush called Luminosity. This makes sure that shadows don't appear behind transparent panels without a cutout, and there will be an API for additional customization.
You can use the new build alongside of previous builds, which means that this can run in a production environment as long as your app still targets a production version of Windows 10 when you submit it to the store. Unfortunately, you need to run SDK build 18312 on an Insider Preview build of Windows 10 though.
To download Windows 10 SDK Preview build 18312, you can find it here. Also, there are new images for the Desktop App Converter, Assessment and Deployment Kit (ADK), Windows Deployment Kit (WDK), and Hardware Lab Kit (HLK).