I can't imagine what NT existence would be like, so I it is impossible to form an intelligent opinion on either of the first two points.
I was diagnosed last year while in therapy for other things, which brought up asd as a causative. I have had a little bit of social training, but not after the diagnosis: just a communication class when I was maybe 20. It helped a little. What helped most, though, was methodical observation and mimicry of the patterns of others I observed in successful interactions. Also stage acting, surprisingly enough, was liberating rather than terrifying... I knew exactly what to say.