The main streets are the following: East 2nd Avenue, North Prairie Street, West 1st Avenue.
You can find 1 post offices locally like "Flandreau Post Office" In term of police stations you can find 1 location in the region (like "Flandreau Police Department"). For banks and/or ATMs you have 1 places with "First National Bank" for example.
About restaurants, 1 possibilities exist (like "John's Place").
Are you looking for an apartment for sale/rent? Or interested by a house? You can check that on Zillow.