There is an online tree at ancestry.com that belongs to a granddaughter of Minnie Elise Erickson, born 26 Feb 1893 in Washburn, Minnie is the daughter of Emil Erickson and Maren Anderson. According to the owner of the tree, Emil was born in Eiker, Buskerud, and was the son of Erik Christiansen. She lists Maren as the daughter of Andrew Engedahl.
The graves and all the census records you haved listed are correct, so you have found th correct family.
Hilsen fra Tyskland,