One of the reasons the Soviets backed down in Cuba was because they did have the ability to strike us beyond the coasts.
But our position vis-e-vis Georgia is far more similar to that of Soviets in 1962 than it is to the Americans then. Georgia is a small country on Russia's borders, traditionally subservient to Moscow, which has had a revolution installing an ideological group allied with Russia's enemy on the other side of the world. That enemy has attempted to arm Georgia, and Russia has invaded, as the United States would have done in 1962 had there not been missiles in Cuba.
The fact was, that in 1962 the Russians could not have stopped a US invasion of Cuba militarily, just as we could not have stopped an invasion of Georgia directly. Therefore they were left with the choice of escalating things else ware or giving in. They initially escalated things else ware, but rapidly decided it was not worth the cost. We did the same, only our calculation was that it was not worth cutting of the EU's natural gas supply to kick Russia out of the G8.
Probably enough to do some real damage. The benefit of having ten times the nukes you need is that even with a 90% failure rate, you still succeed in hitting things. Not that it is likely to come to that, since Georgia is not worth it to the United States. The real question is whether Georgia is worth that much to Russia.
Even if it triggered World War III? Our forces would very likely have gotten into a shooting war with the Russians, and at the time the Warsaw Pact had an overwhelming superiority in conventional forces. Our entire strategy called for us to go Nuclear almost immediately because we would be rapidly overrun otherwise. It wasn't until Reagan that we had the ability to go toe to toe with the Russians without Nukes. Would Hungary really have been worth Italy/Germany/France being overrun and/or a nuclear war?