Why does it say "At Keruv mi'Meshach ha'Sochech"?
Rashi: You are the bird of size, i.e. the great bird that its wings cover much. I.e. you have a great rule. "Mi'Meshach" is an expression of large; the Targum of "Anshei Midos" (Bamidbar 13:32) is (Gavrei) [Anashin] d'Mishchan.
Rashi (16, citing a Midrash): Are you like the great Keruv, which covers the entire Shamayim, from one end to the other?
Radak: He is compared to a Keruv, due to his great level. Mi'Meshach is grandeur, like "Al Tig'u vi'Mshichai" (Tehilim 105:15). It says ha'Sochech, for he is compared to a Keruv, about which it says "Sochechim b'Chanfeihem" (Shemos 25:20). I.e. he covers his nation. Mi'Meshach is an adjective; it is not Samuch to ha'Sochech, even though it has a Patach under the Shin, just like "u'Miksam Chalak" (above, 12:24).
Radak citing [the grammarian] R. Yonah: Sochech is the good oil used to anoint kings. This is like "V'Soch Lo Sachti" (Daniel 10:3). Mi'Meshach is an adjective; Samuch [to ha'Sochech].
Malbim: His flag had the form of a Keruv of olive wood, covering over the Aron.
What do we learn from "u'Nsaticha b'Har Kodesh Elokim Hayisa"?
Rashi: I gave to you a place to acquire fame, in building My Kadosh mountain. You helped Shlomo with cedar trees (Melachim I, 5:22-24).
Rashi (16, from Bava Basra 75a): Did I put you to be in My Kadosh mountain, like I put [the great Keruv]?
Radak: "U'Nsaticha" - I gave to you this grandeur, and you did not know Me, and you became haughty over My nation! "B'Har Kodesh Elokim Hayisa" refers to the previous Melech Tzor (Chiram), who was good. He was in Har ha'Kodesh (Yerushalayim), and he sent trees to Shlomo to build the Beis ha'Mikdash, like it says in Melachim I, Perakim 5-7.
Malbim: You dwelled in Har ha'Kodesh special to Hashem, i.e. the Beis ha'Mikdash in Har Tziyon ? this was in your life.
Did he walk amidst stones of fire?
Rashi: You acquired for yourself a remembrance with Malchei Yisrael, who are like angels.
Radak: Yisrael are called Avnei Esh, for they were Am Kadosh.
Radak citing his father #1: This is said in astonishment. Did you walk amidst spiritual bodies of supreme fire?!
Radak citing his father #2: You walked among carbuncle stones, that illuminate like fire; they brought them in front of you in place of lamps, to illuminate at night. Therefore, you thought that you are a Keruv!
Malbim: Yes, after death you went under canopies of gems in Gan Eden. There, [the gems] are of fire, and not from earthly substances like our stones.