I'll snag the easy one.

The de facto policy from 1866 to the present day has been that the family receives a KIA notice, but are not told by an official U.S. representative that the service member had been executed for desertion.

Just one American service member has been executed since the Civil War for desertion alone (i.e. not for desertion + murder, rape, etc.). U.S. Army Pvt. Edward Donald Slovik was killed by firing squad on 31 Jan. 1945 in Sainte-Marie-aux-Mines, France.

His wife, Antoinette Slovik, learned about his death in March 1945, but didn't learn until 1953 that he had been executed by the U.S. Army, during an interview with an author writing a story about her late husband.

Source: Fraser, C. Gerald. 8 Sep. 1979. "Antoinette Slovik, Widow of a G.I. Shot by Army for Desertion in 1945". The New York Times. https://nyti.ms/311grQo retrieved 30 July 2019