What was the result of the crises over Cuba and Berlin during the Kennedy presidency?
To the extent that these two crises (I am leaving out the Bay of Pigs, since it is not usually seen as a crisis on the same level as the other two) have a common result, their result was to strengthen the perception of American power. Both of these crises, arguably, ended in ways that were favorable for the Americans.
In both crises, the Soviets were the ones who essentially backed down. In Berlin, the Soviets had demanded that Western forces be withdrawn from West Berlin. The West did not comply and, after the crisis was over, their forces were still in the city. In addition, President Kennedy burnished the reputation of the US with his speech in West Berlin in which he pledged to stand by the people of that city. In the Cuban Missile Crisis, the Soviets backed down once again. They had sent nuclear missiles to Cuba, but they removed them after the confrontation between them and the US in October of 1962.
In these two crises, then, the US came out on top both times. In each case, it appeared that the Soviets had to back away from the positions that they had taken at the start of the crisis. This made them look weaker and made the Americans look stronger.