The Windows 10 SDK (10.0.10586) for the November 2015 update of Windows 10 (a.k.a. Version 1511) is now available. It can be installed via an optional install with VS 2015 Update 1 or as a standalone installer. This includes DirectXMath 3.08, Direct3D 11.4, Direct3D 12.0, DXGI 1.5, updates to Direct2D/DirectWrite 1.3, and XAudio 2.9. See What's new in Windows 10 for developers, build 10586.
DirectX Developer Runtime: The DirectX Developer Runtime for Windows 10 is an optional feature called Graphics Tools as described in this blog post. When upgrading from 10240 to 10586, the optional feature can be disabled rather than updated, which can be fixed by re-enabling the optional feature. Note that WARP12 is part of the Graphics Tools optional feature as it's currently intended only for use by developers.
XInput: For UWP, you can continue to use the XInput 1.4 API but need to change from linking to
xinputuap.lib. Alternatively, you can make use of the GamePad class in DirectX Tool Kit which uses the new
Windows.Gaming.Input API. See XInput and Windows 8.
XAudio: With the Windows 10 SDK, if you are linking with
xaudio2.lib you are linking against XAudio 2.9 and should build your application using
_WIN32_WINNT=0x0A00. If you want to use XAudio 2.8 with the Windows 10 SDK, you need to set
_WIN32_WINNT=0x0603 and link against
xaudio2_8.lib. See XAudio2 and Windows 8 for more details.
VS 2013 Users: As with the past few releases, the Windows 10 SDK only integrates with the latest Visual Studio, VS 2015. You can use the Windows 10 SDK with VS 2013 by using the props attached per this Visual C+ Team Blog.
Samples: As with the Windows 10 SDK RTM, official Windows samples are hosted on GitHub: Windows-universal-samples, Windows-classic-samples, Windows-driver-samples. Additional Direct3D 12 samples can be found in DirectX-Graphics-Samples. See also DirectX SDK Samples Catalog.