Operations in the graphics pipeline

I have a few short question regarding operations happening in the rendering pipeline (OpenGL, Vulkan, I’d expect for all questions to have similar answers for these two frameworks while DirectX might work a bit different).

Is the division of the coordinates x/w , y/w , z/w the last operation that happens on the GPU? Or are there other operations that happen afterwards? I wasn’t really able to find any information on that, could anyone point me into the right direction?

Furthermore, concerning the depth of fragments, as far as I understand a quantization takes place to discrete units of depth, but I couldn’t find anything detailed if these operations follow some kind of IEEE standard or if they have their own standards, maybe even depending on the manufacturer. Does anyone know more detail about this or could point me into the right direction?

In general are there some, more or less, complete information about the possible operations (besides of course programmable operations during the programmable shader stages), the error bounds, etc. for operations on the GPU, is there maybe a white paper from NVidia regarding this or can anyone give me a hint on where to ask this question or find in depth resources?

Kind regards and thank you in advance.