1)
Why does it mention now covering the floor with gold?
1.
Malbim: They did so after putting the Keruvim inside, lest the covering be ruined when going there 1 or when making the Keruvim.
1
In any case, twice every day a Kohen enters the Heichal to burn the Ketores and light the Menorah! Perhaps we are more concerned for the Kodesh ha'Kodoshim, which is entered only twice a year. (PF)