What is the significance of the triple blessing "Va'aheivcha, u'Veirach'cha Vehirbecha"?
Ramban #1: If Yisrael will keep the Mishpatim out of love of Hashem, 1 then He too, will love them, bless them and increase them.
Ramban #2: With reference to the judges who perform Mishpat, "Va'aheivcha" - Hashem will cause the families whom they have found guilty to love them: "u'Veirach'cha" - no harm will befall them (the judges) following their harsh judgment: "ve'Hirbecha" - they will not decrease on account of the death of the sinners, even if this entails many people, such as in the case of an Ir ha'Nidachas.
Ba'al ha'Turim: "Va'aheivcha" - on the merit of Avraham; 2 "u'Veirach'cha" - on the merit of Yitzchak, 3 and "Vehirbecha" - on the merit of Ya'akov. 4
Oznayim la'Torah: The Torah inserts "Va'ahevcha" before "u'Verach'cha" because a B'rachah that is given without love is not a complete B'rachah. 5
Refer to 7:12:1:2**.
About whom the Pasuk writes in Yeshayah, 41:8 "Zera Avrahm Ohavi" (Ba'al ha'Turim)..
About whom the Torah writes in Chayei Sarah Bereishis, 25:11 "Vayevarech Elokim es Yitzchak" (Ba'al ha'Turim)..
Whom Hashem blessed with the words "P'rei u'Revei" - in Chayei Sarah Bereishis, 35:11 (Ba'al ha'Turim).
Which explains why the Kohanim recite the B'rachah 'Levarech es Amo Yisrael be'Ahavah'. See Oznayim la'Torah.
What are the implicatons of "P'ri Bitn'cha"?
B'rachos, 51b: It implies the Beten of the man and not of the woman - to teach us that the B'rachah of the children that the wife bears comes about through her husband. 1
Perhaps the Gemara does not make a similar inference from "Admasecha, Degancha Tiroshcha and Yitzharecha" because, whereas land and fruit can be owned by a man or by a woman, children are the product of both, in which case the Torah ought to have written 'P'ri Bitn'chem' or 'Beten'.
What is the definition of "Sh'gar Alafecha"?
Rashi: It means 'the babies of your cattle'
See Peirush Yonasan.
What are "Asht'ros Tzonecha"?
Rashi #2 (citing Targum Onkelos) and Targum Yonasan: 'Your flocks of sheep'.
Rashi #3 (in Ki Savo, 28:4, citing Chulin 64b): They are called "Ashtaros" because they enrich their owners ('Ma'ashiros Ba'aleihen) 3 and strengthen them
Rashi (Ibid.): Like the Pasuk in Tehilim 22:13 "Abirei Bashan"