Depth Stencil buffer mandatory?

Question

If I disable depth and stencil buffering, do I have to create and set the depth stencil buffer?

Answer 1

You do not, calling ID3D11DeviceContext::OMSetRenderTargets with the DepthStencilView parameter being a null pointer is perfectly valid, and you can still draw fine:

Obviously though, whatever you drew last will be drawn on top of everything else, regardless of its actual Z position - the colorful triangle in the image is behind the white one, but was drawn last.