I grew up not too far from Iroquois - it is a VERY small town Id guess 250 give or take people, but does have their own school in town (but not much else)
It lies in Kingsbury county so you may want to search for the county web page and check tax rates - lots of hunting in the area, and some nice lakes for fishing as well.
The closest larger town is huron, and they still dont have much their either honestly (home of the state fair)
Weather wise - warm humid summers - just like most of easter SD - always a chance of storms or tornados (actually an even smaller town close by Iroquois, Manchester, was hit HARD by a tornado a few years back). Winters are hit or miss - sometimes lots of snow, sometimes not too much, but chilly (again like most of eastern SD).
good luck!