And as far as Vietnam... any major withdrawal before the end of 1964 is impossible. And by that point, JFK has likely made many of the same decisions as his successor did- decisions that will force him onto the same path. In the first few months of 1965, he will sadly announce to the public that their husbands, fathers, and sons are needed in Vietnam, but only for a few months until the situation is pacified and they can leave...
I'll direct you to this site, which publishes archival gov't documents, some of which elaborate on Kennedy's plans for withdrawal from Vietnam, had he lived.