1)
Why is there an extra 'Mem' in "ha'Pidyom"?
1.
Rashbam: The Torah sometimes adds 'Mem'. 1
1
Rashbam: Like we find in Bereishis, 41:32 "Reikam", and in Sh'mos, 8:13 "ha'Kinam".
2)
To whom is "Peduyei ha'Levi'im" referring?
1.
Rashi: It refers to the twenty-two thousand firstborn who were redeemed by the bodies of the twenty-two thousand Levi'im.


