Where did the Keruvim stand?
'Rashi': They stood on the floor, in the west of Kodesh ha'Kodoshim. (One was north of the Aron, and one was to the south - Rashi Melachim I, 6:24.) Their wings were over the Aron and Moshe's Keruvim stuck on top of the cover of the Aron. Do not be astounded that Shlomo made additional Keruvim. He also made 10 Menoros and 10 Shulchanos in addition to those of Moshe!
Here it says that that the Keruvim faced the Bayis. Shemos 25:20 says that they faced each other!
'Rashi', from Bava Basra 99a #1: They face each other somewhat, and also face inside the Bayis somewhat (Radak ? like a Talmid taking leave of his Rebbi).
Radak, Malbim: Moshe's Keruvim on the Aron faced each other, but Shlomo's Keruvim faced the Bayis, just like they stood differently - Moshe's were on the Aron, and Shlomo's were on the floor. Malbim ? Moshe's Keruvim hint to when Yisrael do Hashem's will. Influence comes from the Aron, on which they Keruvim face each other, and we receive from Hashem without an intermediary. Shlomo's Keruvim hint that even when Yisrael do not do Hashem's will, they stand in front of the Aron and receive from Hashem via an intermediary. They faced the Bayis, and did not receive from each other.
Basra 99a #2: When Yisrael do Hashem's will, they face each other. When Yisrael do not, they face the Bayis.
