I think we . . . are risking some error . . . to assume that our definition of Good was God’s definition at a precise point in time.
God declares that His ways are beyond finding out. Yet, we persist in taking very finite phrases and construing all manner of air castles from them.
God made very clear what He wanted to be clear about establishing and maintaining a relationship with Him.
He left a lot of things slightly hinted at. Taking such hints and writing long, thick tomes about them seems like extreme vanity, to me.
The ‘angels’ were a part of the creation, they are not a part of God.
They possibly were created before man, but there is nothing in scripture to support that, one way or the other, but the fall was definately after day six, or the creation could not have been called “very good” in truth. A fallen system is not very good, and even Lucifer, before he acquired lust, was also very good.