1)
Why does the Torah write "Vayicht'vu" (plural)? How can two people write simultaneously?
1.
Moshav Zekenim (citing R. Yehudah ha'Chasid): It is because they needed to write Hashem's name, which required ten men to oversee the writing 1 and to have the correct Kavanah. 2
1
See Oznayim la'Torah who queries this and elaborates.
2
From here we learn that someone who writes Names of Hashem in a Seifer Torah, Tefilin or Mezuzah must do so in front of ten [men] and Tovel [beforehand] and be in a place of Taharah - since a matter of Kedushah cannot be performed in front of less than ten men.
