Is it necessary to include the preposition "in"? It seems with describing the colors of other objects we just wrote, for example, "Le camicie sono bianche e nere."
Yes, if you were describing their color you'd say "i loro giornali sono bianchi e neri", while "in bianco e nero" refers to the way they present their content, black&white vs color.
They should be more tolerant of typos and writing mistakes. I wrote "nero" with double "r" and lost a heart. In German tree such mistakes are always tolerated.