Russia used up its ammunition, trust me, they didn't use 15% of their ammunition in WW2...

They didn't use paratroopers in the winter war because they didn't need to and the paratroopers weren't that good. The Soviet Paratroopers mostly fought as ground infantry in WW2 because they weren't that good at drops and the Russians didn't have a good airforce anyway. But the Soviets had a very large number of paratroopers, that were useful on the ground during WW2, so they were applied in that manner when needed.

Russia didn't invent "blitzkrieg". Blitzkrieg is a continuation of classical German maneuver warfare tactics from the 1700 and 1800s but applied to modern technology at the time, tanks, aircraft, infantry, artillery, etc. What the Russians had was deep battle, and a similar fascination with tanks and paratroopers... but the Soviet Deep Battle was different in that it was focused on the tactical level, striking far behind enemy lines, as opposed to the blitzkrieg with was tactically focused.

German Generals also claim they didn't invent blitzkrieg, the media did, which may be right as well.