Is there a specific & significant .. midrash / point .. to distinguish between: ELIJAH & Chariot of Fire (being taken up in a whirlwind) ..VS.. EZEKIEL & the Mercabah Chariot of Fire (Chpt 1 & 2); ... & .. is there a metaphoric message to the congregation?

The connection which you correctly suggest is explicitly found in the Talmud Yerushalmi (Brachot 5, 1), which recounts a midrash that one of the opinions that Elijah and Elisha were talking about at the time of Elijah’s taking in the “chariot of fire” was about the Merkava Chariot as seen by Ezekiel. Another opinion there is that they were discussing the Creation of the world. Both of these topics are referred to by our rabbis as the two “great topics” (Brachot 58a; Sukkah 28a) which are at the very heart of kabbala, and we obviously cannot elaborate on such deep topics in the scope of this framework (Hagiga 11b). Please ask your local orthodox rabbi. With Love of Israel, Rav Ari Shvat