Although I haven't written a compute shader yet, compute in Vulkan looks trivial to use once you have waged your initial battles against the rendering pipeline setup. Most of the complexity with Vulkan lies in understanding descriptor sets, pipeline layouts and pipeline objects. I find that the Vulkan interface is remarkably consistent once you get over the initial - and substantial - hurdles.
Vulkan Compute shaders work in recent Android devices and on every Windows/Linux PC that has a <5 year old dedicated GPU. And for iOS/OSX there is an interop layer in the works that will enable Vulkan over Metal.
Actually no.
Vulkan is an optional API, so unless we are talking about Samsung and Google flagships phones, there is no guarantee of it being available.
So far Google hasn't even bothered to add it to the dashboards.
For compute, only Renderscript is required.
From the article suggests at some point OpenCL is going to run on top of Vulkan.
In compute you just dispatch kernels and put barriers to prevent race conditions. Pretty much like OpenCL Out Of Order queues except the arguments are passed via descriptor sets rather than given individually.
I want Vulkan compute.