You have included a lot of very useful information - wonderful! One thing missing is your request or question - not sure what you are looking for? For sure you want to know the maiden name of Ernest's wife, yes? Her parents, and specific place of birth?
Karl and Katherine Hoesch of Huntley, Harlan, Nebraska had a son Ernest. They immigrated in 1883. They seem to be the parents to “your” Ernest. Obituaries:
The Karl Hoesch family were members of the Evangelical Lutheran Church of Huntley (in Harlan County, Nebraska). That church might be the place where Ernest was married and thus might have a record of his wife's maiden name.
"Carl" Hoesch appears in the 1890 edition of the Harlan County, Nebraska Farmer's Gazetteer, listed as living in Huntley.
The Hoesch Memorial Library was built in the city park in Alma, Harlan County, Nebraska, in 1978, a gift to the community by Albert Hoesch "in honor of his pioneering parents, Karl and Katherine Hoesch." http://www.casde.unl.edu/history/counties/harlan/alma/http://www.casde.unl.edu/history/counties/harlan/alma/
I'll look into Ernest's wife Katherine some more and maybe other volunteers will help. But since the Hoesch family did not move around, one guesses that Ernest and his wife met in Harlan County, Nebraska.
He is German and she is born in Russia. Most immigrants in Nebraska of this era who were born in Russia were typically "Germans from Russia," many of whom were "Volga Russians" and that might be a starting hypothesis for finding out Katherine' identity (if their marriage certificate cannot be found at the Harlan County courthouse and if their children's birth certificates do not contain her maiden name and if her death certificate does not contain her maiden name. Those obviously are the places you would first look).
There were unique colonies of Germans in Russia who immigrated there beginning in the 1700s but were given much autonomy. They never considered themselves Russian, even over several generations, and still spoke German, governed themselves, maintained their German customs and religion etc. This autonomy was part of the original deal as an incentive to settle in Russia. Conditions in the late 1800s led many of them to flee their German settlements within Russia: famine, a shift in the political policy toward them, discrimination etc.
A center for the study of Germans from Russia is located in Lincoln, Nebraska. A very active genealogical society has done exhaustive research on the connection between Nebraska and the German colonies in Russia.
I will try to get back to this but for now the above is "off the top of my head" and maybe it will help.
Meanwhile you'll let us know more specifically what you are needing - or let me know if I'm guessing right that your focus is on finding Katherine's maiden name and origins.