Short answers, pulled from the story.
Lazar Markovich Lissitzky was born on the 23rd of November 1890 in Pochinok, a small Jewish community southeast of Smolensk. His family lived in Vitebsk from 1891 to 1898 before moving to Smolensk in 1899.
The term Proun pronounced pro-oon stands for UNOVIS Project and refers to abstract geometric paintings developed between 1919 and 1920. These compositions functioned as architectural versions of suprematism with neither top nor bottom orientation.
Marc Chagall invited El Lissitzky to return to Vitebsk in May 1919 to teach graphic arts at the newly formed People's Art School. Chagall had been appointed Commissioner of Artistic Affairs for Vitebsk in 1918.
El Lissitzky died on the 30th of December 1941 in Moscow while continuing to work despite worsening tuberculosis. He suffered from the illness during his stay in a Swiss sanatorium in 1924 and 1925.
Wolkenbügel or cloud-hangers were flat three-story one hundred eighty-meter-wide L-shaped slabs raised fifty meters above street level intended to mark major intersections of the Boulevard Ring in Moscow. Each structure rested on three pylons that doubled as staircases into proposed subway stations.