I installed that updater thing, and now the setup and client apps wont open at all
From what I understand, the updater shouldn't be run at this time. Because you ran it, I think you'll need to reinstall in order to fix the fact that you just filled your client with a lot of outdated files. You will note that you were told to read the Mac Client Status before following the Mac guide, and I will note that it says "Do NOT run the updater as the binaries have not yet been uploaded yet."
You were having graphical glitches, it had a point for those with graphical glitches... after reinstalling, because that's what I think you'll need to do, try solving your problem by following point "IMPORTANT1" in that guide.
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Although I was under the impression that it's now off by default--it's certainly off already in my download.