Re: Move to Zumikon
I think you'll find Zumikon a superb place to live and especially attractive on your taxes. It has probably the nicest Migros grocery store in Switzerland and lots of English speakers which will ease your entry to living and integrating here. I miss walking the Tobel along the river down to Lake Zurich.
Yes, 1 August is Swiss National Day holiday but a great day to start the Swiss chapter of your life. If you are outdoorsy, how about watching some fireworks? Suggest the top of either the Wehrmännerdenkmal (short walk) or the Pfannenstielturm (a nice walk in the woods to reach it, or you can drive a bit closer.) Just take the train from Zumikon one stop south to Forch.
If you child is attending ICSZ, see if you can get a copy of last year's welcome/contact booklet printed by the parent's association. It will help tremendously in getting situated with doctors, municipal and other services, where to get things, buying stuff from people moving away, etc.
BTW, if you get desperate for things when shops are closed, you can always take train to Zurich main station or Zurich airport where Migros are open on weekend/holidays I believe. Best of luck and welcome!