Why does it say "Zeh Devar Hashem El Zerubavel"?
Rashi: This is a sign for you to promise Zerubavel - just like the olives and oil are finished automatically in every way (Radak - no one arranged the Neros or poured oil into them), so you will not build My house via your strength.
Malbim: He informs that the Menorah hints that when He will bring Avdo Tzemach, from the seed of Zerubavel. Then, Hashem's conduct will be without intermediaries. It will not be via the Ma'arachah - then, one needs strength to overpower via nature. It will not be via the angels - then, even though it is miraculous, without external power, inner strength is needed. Miracles do not rest on something empty - "Lech b'Chochacha Zeh v'Hoshata Es Yisrael" (Shoftim 6:14).
Why does it say "Ki Im b'Ruchi"?
Rashi: I will put My Ru'ach on Daryavesh, and he will let (some texts - command) you to do all needs of building from his [money], and help you with wheat, wine, oil and trees, like it says in Ezra. You will not need the help of any [other] man.
Malbim: Ru'ach Hashem alone will conduct and rule with Hashgachah Pratis. The gold Menorah and seven Neros hint to this, with the seven eyes [hinting to Hashgachah] of Hashem carved into the foundation rock.
