Why did Yisrael refer to the attackers as "ha'Am ha'Zeh" and not mention them by name?
Rashi: Because they were uncertain of their identity, since they wore the clothes of Amalek but spoke the language of Cana'an.
What are the connotations of "Ve'hacharamti es Areihem"?
Rashi #1, Ramban, Rashbam and Eruvin, 64b: It means that they declared the property Hekdesh 1 (and we learn from her that, if one acquires the property of a Ger who died, one should perform a Mitzvah with it in order to ensure that it lasts ? Eruvin). 2
Rashi #2 (in Sanhedrin, 43b): It means that they declared them Asur be'Hana'ah. 3
Targum Onkelos and Targum Yonasan: It means that they would completely devastate the towns.