Short answers, pulled from the story.
The word blitzkrieg first appeared in a German military periodical called Deutsche Wehr in 1935. It described quick or lightning warfare but had no connection to armored units or air forces at that time.
Adolf Hitler later dismissed the term as completely idiotic in a speech delivered in November 1941. He claimed he never used the word himself and called it Italian phraseology by January 1942.
German strategic thinking derived from writings by Carl von Clausewitz who lived between 1780 and 1831. Helmuth von Moltke the Elder served as a general from 1800 until his death in 1891, and Alfred von Schlieffen died on the 4th of January 1913 after advocating maneuver and mass to create decisive battles.
Operation Barbarossa produced nearly 3.5 million Soviet prisoners along with masses of equipment. The Kesselschlacht or cauldron battle inflicted losses primarily through mass capture of prisoners and weapons.
French Prime Minister Paul Reynaud analyzed the collapse in a speech delivered the 21st of May 1940. The same French Army collapsed after barely two months fighting contrasting four years trench warfare from First World War.