1) If you have arrived here after already finding your type in Myers-Briggs, especially if through a MBTI test, do not assume that your Socionics type, as defined by Socionics theory, corresponds to the MBTI you have found for yourself. You should look at your Socionics type from scratch.
2) Socionics types are not related to MBTI through a J/P switch for introverts. That works only if you are defining types according to ego functional ordering and assuming that Socionics functions = MBTI functions. That is however not helpful to find your true type, either in Socionics or MBTI.
3) Typing by VI - Visual Identification - is not something that can be easily learned or applied simply by looking at pictures of people of a certain type, much less by correlating specific facial features (length of the nose, thickness of lips, etc) to Socionics characteristics. It only makes sense to try to use VI after you already understand Socionics and have observed enough individuals of each type.
4) Socionics - like Myers-Briggs - has Carl Jung's Psychological Types as its starting point. It is definitely useful to read Jung's writings on that. However, Jung's types and functions are not the "true" Socionics types and functions. It makes no sense to argue Socionics from a purely Jungian standpoint. It's necessary to understand Socionics functions also independently from Jung.
5) Socionics is not a personality theory in the sense of personalities as mainly defined by external behavior traits. Socionics's types are defined ultimately by deeper personal priorities and motivations. However, external behavior traits provide clues as to the person's priorities and motivations.
6) Socionics is an interpersonal relationship theory. However, the Socionics relationships only work as described in situations where all other external factors are relatively neutral. Everyone understands that many factors (age, culture, family relationships, professional relationships, etc) influence interpersonal relationships. All those factors being equal, however, relationhips do work as described by Socionics, especially over time.
7) Duality is not some sort of "mystical experience" as some descriptions sometimes may suggest. Your dual is simply someone whose company, by temperament and functional preferences, is most comfortable for you, since your dual appreciates and needs precisely what you regard as your strengths and is most happy to help you and support you precisely in those areas you most appreciate it. However, you may still not get along with your dual if s/he is your boss, your rival, your superior officer, your teacher, someone of a very different culture, etc.