Kabbalah, Gematria, Holiness (and Maimonides)

I recently heard a class which left me very confused. The instructor, who claimed to be an orthodox rabbi, spoke about Maimonides’ rejection of Mysticism. Among the mystical ideas that he supposedly rejected was that:
The Hebrew language is intrinsically holy [citing the Talmud and Mishna as being against this, i.e. the concept of gematria, etc.]
The Jewish people are a holy nation
The Torah or mitzvot contain any intrinsic holiness, [there’s no intrinsic difference between the Torah and Shakespeare]
The Land of Israel has any intrinsic holiness. He taught that to believe any of the above is idolatrous since it is assigning godliness to things that don’t have it, which is precisely why Maimonides waged a war against these ideas which are truly foreign to traditional Judaism.
So perhaps you could clarify:
Are the above ideas mystical/idolatrous ideas?
Was Maimonides really against mysticism, [as was the Talmud, according to this presenter]?

Kabbalah

I have noticed that you often offer explanations to the Torah from the “Kabbalists” or “Kabbalistic Masters”. Who are these people and how do they differ from the standard rabbinical analyses and explanations? Are they Jewish mystics?