I had all those problems and I reverted the driver to .075. This mostly solved the wifi drop out problem.
A couple of days ago, the new Atheros 10..0.0.218 appeared in the Acer LIVE updater, which I then installed; I have had no wifi dropouts so far. Not sure where you got your 10.0.0.221 from? Anyway, just a suggestion, activate your Live Updater, and try the .218, maybe that will fix it.
It's been 7 days since we bought this ultrabook and we couldn't figure out how to fix the wifi issues. It connects and disconnects. We tried to install the latest wifi drivert as well, but that makes it even worse. We couldn't connect. Please someone help...