False, CR himself has stated that SM is in PU.
Not true. Please provide source.
No, it isn't low. Look at any early access game, while they are somewhat buggy, SC is borderline unplayable. Show me one game where the netcode reduces the FPS, where you can repeatedly walk through almost any wall, where your goddamned weapon doesn't render because you aren't wearing right clothes.
Early access games usually tend to be complete **** precisely for the reason that the devs are too afraid of introducing bugs and so they get locked down and never get finished. Compared to your average early access game, SC is more buggy but also changes a lot more. Which is as it should be. Also, SC is not really early access, more like complete access, even pre-Alpha stages of development can be played. You cant expect a polished product at that stage.
SC is not unplayable at all.
Those bugs you mention are trivial things that may not be acceptable in a released, finished game, but are totally fine in a WIP product. Most ordinary games with closed development would be much more buggy still.