Why did Avraham mention above (in Pasuk 3) that Hashem was also "G-d of the earth", but omit it here?
Rashi: Refer to 24:3:4:1.
Ramban, Seforno: Refer to 24:3:4:2,3.
Malbim: Hashem alters the arrangement of Mazalos in Shamayim. In Charan, I was Avram, who cannot father children. Hashem brought me here, changed my Mazal, and swore to give the land to my seed. Surely He will arrange that she come to here!
Rashbam: In this Pasuk, Avraham was telling Eliezer that the G-d of the Heaven (who was his master) would certainly send an angel to guide him (Refer to 24:7:2:1).
On what basis did Avraham inform Eliezer that Hashem would send His angel to guide him?
Rashbam: Since Hashem, G-d of the Heaven, brought him to Eretz Kena'an, Avraham knew that He did not want his children to move away from there, in which case He would certainly send His angel to help Eliezer succeed on his mission - in finding a wife in Charan.
Seforno: Avraham was praying to the G-d of the Heaven to send an angel from His Heavenly realm to guide Eliezer, so that it would not be necessary for Yitzchak to go there himself. 1
What is the significance of the double expression "el Artzi ve'l Molad'ti"?
Rashbam and Ramban: Refer to 24:4:1:1.
Rashi: "Artzi" refers to Charan (where he lived), and "Moladti", to Ur Kasdim, where he was born, 1 from both of which Hashem took him out.
See Ramban, who refutes this explanation for a number of reasons.
Hashem swore that He would give the land to his children by the Bris bein ha'Besarim (15:18-21). Where did He also tell him that He would?
Seforno: He said that He would in Vayeira (21:12). 1
Rashi: Hashem may well have told him this; but "Diber li" means that Hashem spoke (not 'to me', but) about me, which is what "li", "lo" and "lahem" next to Dibur always means. 2
Why did Avraham mention the oath that Hashem had made to him?
Seforno 1 : Having sworn to him, Hashem would be sure carry out His oath, to see to it that Yitzchak would marry the right woman, to ensure that his oath would be fulfilled. And to that end He would be bound to send His angel to guide Eliezer.
Ha'Emek Davar: Since it is my birthplace, there should be Hashgachah that she will come. If I am not worthy for this, Hashem's promise will cause it. If I forfeited this due to sin, in any case He will fulfill his Shevu'ah.
Why does it say "Malacho", which implies a special angel?
Ha'Emek Davar: Hashem will send an angel special for this. He will not use the angel 1 that normally accompanies a person. This is why it says Yishlach, and not Yetzaveh.
Ha'Emek Davar: Two angels normally accompany a person, to testify about his actions (Ta'anis 11a). Hashem also commands them to guard him.
Why does it say "mi'Sham"?
Ha'Emek Davar #1: Be Mekadesh her Stam [to Yitzchak], and do not mention [until later] that she must come to here.
Ha'Emek Davar #2: If you cannot get a girl from my family, take a girl from the place.