There is no such trinitarian theology in Judaism. By this reasoning, one could claim that each of the ten sefirot of kabbalah mysticism was a distinct person of the Godhead. But this is taking literally what is intended figuratively. In Jewish theology, for example, the shekinah, or Holy Spirit, is simply the manifest presence of God in the world; it is not a separate person within the divine Being. To render it in Christian theological terms, Jews believe in one hypostasis and one ousia.
No there isn't. Which doesn't mean it isn't true, or that it is not hinted. Hypostasis simply means something that has existence, such as your words. But they are not just sequences of letters; they contain in them your mind and your spirit at the same time.
I am not familiar with the sefirot, or how they come about, but I think you are taking the word "person" too literally. There is one God; we know of Him through his manifested energeias (workings): Wisdom, Word and Spirit.