Nice forum! Respect to all members!
1)If full-scale nuke war start, that both country could become a desert. If quantity of warhead was reduced to 1200 units each side, that, according MAD, country has done first strike would lose more civilian bcz main targets of first strike are ICBM launchers and other strategic targets. Attacked side have to nuke enemies cities to revenge.
2)The USSR has had defense doctrine to prevent new invasion from Europe like 1941's one by Hitler and 1812's by Napoleon. The SU never was able to do land forces invasion to US, but US has platzdarm in Europe to such invasion to the USSR. However, the SU had numerical land forces superiority enough to reach La Manche.