USA, Canada / POLISH AMERICANS UNAWARE of KOSHER FOOD TAX? [19]

Sigh. Before believing information like these, check snopes.com (the best source for urban myths online) -> snopes.com/racial/business/kosher.asp

Genealogy / Looking for Zimmermans born between 1950 and 1970 [6]

You could try registering on nasza-klasa.pl website and try searching here (even though a quick search shows, that there are no registered users being both Zimmerman/ Cymmerman/ Cymerman AND living in Kalisz) - provided you speak Polish or have someone to translate. Mind that their surnames might have changed a bit when they left Poland - most likely, your grandfather's surname in Poland was Cymmerman or Cymerman.