Cuban missiles crisis, how close?

how close did the Cuban missile crisis go to becoming a nuclear war? ive read online that the soviets had luna(FROG) short range tactical nuclear missiles on the coast for anti invasion defence. the americans learned of these only after the collapse of communism in 1992. with an invasion force of a quarter of a million, poised to go into cuba, how much damage would of the luna missiles done(20 kt warheads one report said)? would all of the invading american ships and men have been destroyed? what would america have done when their force had been nuked? other than nuke back, what military options would they have done, could they do an airdrop of paratroopers? what jet fighters did cuba have in 1962, was any soviet jets there? what would have gone off in europe if cuba had gone nuclear?