As for the Kabbalah, this is an interesting topic. Kabbalah is a mystical/esoteric form of belief that rose out of Judaism. The term Kabbalah can be pretty hard to establish. Exactly what is it? For the sake of simplicity, let me give Kabbalah the following definition. Kabbalah is the system of mysticism and esoteric belief which had its heyday during the high Middle Ages in Europe among Jews in Western Europe. Strains of mysticism have developed in all major world religions. Islam has its Sufis. Judaism has Kabbalah. Obviously, Buddhism and Hinduism have many forms of mysticism. Christianity does as well. Christian mysticism was especially influential in the Middle Ages in Western Europe. Important figures in this movement are St. John of the Cross and Theresa of Avila. The Jesuits were highly influenced by mysticism. The important figures in this movement were French or Spanish. It is no coincidence that the most important center of Jewish mysticism in the Middle Ages–of Kabbalah–were French and Spanish.
You ask if early Jewish esoteric mysticism is Kabbalah. This is a question more of definition than history. Like I said already, all world religions have strains of mysticism and esoteric belief. This is as true in Judaism as it is in Christianity or Hinduism. Of course, there were earlier forms of esoteric Judaism, especially in the Roman period, but to say that this is Kabbalah is to push the definition. It is more accurate to say that Kabbalah is a particular form of Jewish mysticism which appeared in the Middle Ages and has been influential and broken out at various times and places since.
So, with this limited definition, what is Kabbalah? For that matter what is mysticism? Mysticism is a form of religion which is highly individually focused which emphasizes a personal inner religious experience. It focuses on methods to achieve an ecstatic religious experience through specific practices such as meditation, mantras, rituals. It typically involves special “hidden” forms of knowledge. For this reason, mysticism and Gnosticism tend to be intimately associated, especially in Christian and Jewish forms of mysticism. Kabbalah is the specific form of esoteric mysticism that emerged in France and Spain in the 12th through 14th centuries. The Kabbalist believes that there are three or perhaps four levels of meaning in the Hebrew text. The levels of meaning are (from the wikipedia article on Kabbalah)
- Peshat (Hebrew: פשט lit. “simple”): the direct interpretations of meaning.
- Remez (Hebrew: רֶמֶז lit. “hint[s]”): the allegoric meanings (through allusion).
- Derash (Hebrew: דְרָשׁ from Heb. darash: “inquire” or “seek”): midrashic (rabbinic) meanings, often with imaginative comparisons with similar words or verses.
- Sod (Hebrew: סוֹד lit. “secret” or “mystery”): the inner, esoteric (metaphysical) meanings, expressed in kabbalah.