1)
What is the meaning of "ve'Hamam Mehumah Gedolah"?
1.
Rashi: 'He (Hashem) will throw them into utter confusion'. 1
2.
Rashbam: He will cause utter confusion. 2
1
Rashi: The second 'Mem' serves as a suffix, because, because, if it was part of the root word, it ought to be punctuated with a 'Patach' - as in Yeshayah, 28:28 - and not with a 'Kamatz'.
2
Rashbam: Since the second 'Mem' is (not a suffix, but) part of the root word, - like we find in Shmuel 1, 7:16 and in Eichah, 5:18. Otherwise, it ought to read 'Veham'mam' (See Rashbam).