1)
Why does it say "va'Yikra" (singular) "ha'Sho'arim" (plural)?
1.
Radak: The guard of the city called to the gatekeepers of the king's house, and they told Beis ha'Melech inside.
2.
Malbim: The Metzora'im spoke to the primary gatekeeper; he gathered all the gatekeepers, and they told Beis ha'Melech.