Radak: This was so if the messengers will go to the roof, they will not recognize their place (amidst the flax; if both were together, it would be noticed).
2)
If she hid the spies after the kings' messengers came, why didn't the messengers see them?
1.
Radak: She already hid them before the messengers came
1
; she sensed that the matter became known to the king.
If so, it should have said "Hi Hitzpinato" (past participle; refer to 1:12:1:1)! Perhaps it says va'Titzpeno to teach that it was after the king sent messengers (perhaps she sensed that they are about to enter her house.
3)
Why did she say that she does not know where they were from, and to where they went?
1.
Malbim: She wanted the messengers to leave quickly to chase them. To support that they are spies, she said that they asked about matters of the land, and concealed and did not say from where they are, and [when they left] to where they are.
