Why is there only one Yud in "va'Yirshu"?
Radak: It is the Yud of the conjugation. The Yud of the root is omitted.
Why is it written uv'Sorosecha, and we pronounce it uv'Sorascha?
Radak: It is written plural, according to the Prat, and pronounced singular, based on the Klal - it is all one Torah.
What is the meaning of "va'Tikrei Osam"?
Rashi: You caused them. It is an expression of Mikra (chance occurrence). Radak - this is like "Ki Hikrah Hashem Elokecha" (Bereishis 27:20). It is written with an Aleph in place of a Hei, the evil that comes to them is not total chance; Hashem caused it.
Malbim: This refers to the third kind of conduct - individuals are rewarded or punished according to their actions.
