Rambam Yesodey HaTorah 2 wrote:
"דְּבָרִים אֵלּוּ שֶׁאָמַרְנוּ בְּעִנְיָן זֶה בִּשְׁנֵי פְּרָקִים אֵלּוּ כְּמוֹ טִפָּה מִן הַיָּם הֵם מִמַּה שֶּׁצָּרִיךְ לְבָאֵר בְּעִנְיָן זֶה.
וּבֵאוּר כָּל הָעִקָּרִים שֶׁבִּשְׁנֵי פְּרָקִים אֵלּוּ הוּא הַנִּקְרָא מַעֲשֵׂה מֶרְכָּבָה: "
"These matters we spoke of on this subject in these two chapters, are but a drop in the ocean of what it ought to be expounded in this subject; and the exposition of all the principles in these two chapters, are known as the Works of the Chariot.
Maase Merkava as I understand it, is a very deep Kabbalistic topic.
Why does Rambam include it in "the Basics of Torah"?
Also do we have any easy commentaries in English online to these first chapters of Hilchot Yesodei HaTorah of The Rambam?