What are the implications of (the otherwise superfluous) words "u'Paschah lach"?
Sifri: It implies that the entire town accept the conditions of the peace terms and not just some of them. 1
See also Torah Temimah, note 47.
Why does the Torah add "Kol ha'Am ha'Nimtza bah"?
Rashi: To include anyone from the seven Cana'ani nations who happens to live there
See Torah Temiah, note 48 and Sifsei Chachamim.
What arethe connotations of "la'Mas Va'avaducha"?
Rashi and Ramban (both citing the Sifri): "La'mas" refers to paying taxes 1 and "Va'avaducha", to being subservient, 2 both of which they are obligated to undertake. 3
Ramban: Inasmuch as the king or Sanhedrin is authorized to claim taxes from them to pay for the royal palace and its store-towns, and for building the Beis-Hamikdash.
Ramban: In that any person has the authority to ask them to chop wood or draw water for him - though he is obligated to pay them the proper wage for his services. See Oznayim la'Torah, who elaborates.
Ramban: Like we find in Melachim 1, 9:21, but not like the Pasuk in Shoftim, 1:28, which relates how the Cana'anim paid taxes but were not subservient.
QUESTIONS ON RASHI
Rashi writes that "Kol ha'Am ha'Nimtza Bah" permits keeping alive a Cana'ani who lives there. But later, in 21:10, he learns this from "Veshavisa Shivyo"?
Riva (in 21:10): If the Torah would have written only "Veshavisa Shivyo", we would have said that the Torah permitted her only because the Yeitzer ha'Ra for a Y'fas To'ar is too powerful to resist, but normally, one may not keep Cana'anim; whereas had the Torah only written "Kol ha'Am ha'Nimtza Bah", we would not know the Heter for a [Cana'ani] Y'fas To'ar, since he appears to be acting against his will 1 . Moreover, our Pasuk is discussing only Avadim, but not marriage. 2 Therefore, both Pesukim are needed.
Gur Aryeh: Do not say that the Pasuk there permits keeping alive only a Y'fas To'ar, since "Vera'isa ba'Shivyah" implies that there are other captives too! Rather, there, they are acquired as total Avadim, and convert (become Avadim Cana'anim). Here they do not, so one might have thought that one may not keep alive any Cana'ani. And had the Torah taught only here, we would have thought that Y'fas To'ar is a Chidush, and a Cana'anis is not permitted.
Mizrachi: The current Pasuk is discussing a town that made peace with Yisrael, whereas the Pasuk there is discussing a town that did not, only Yisrael conquered it, which we would have thought that it is like a city of Cana'anim, and "Lo Sechayeh Kol Neshamah" applies toit. And we cannot learn from there to here, since there we kill all the men, who are the primary idolaters. Here, other nations are not killed at all; one might have thought that also among Cana'anim, we do not distinguish, and kill all of them
Perhaps he means that he cannot resist her, and will do whatever she asks, even to serve idolatry, as occurred with B'nos Midyan (refer to Bamidbar 25:2:2:1 - PF).
We are more concerned that one's wife will entice him to serve idolatry than one's Eved, so perhaps a Cana'anis is forbidden (PF).
