What was special about Avraham's camels?
Rashi: They were different than the camels of others, in that whenever they left Avraham's domain, they left muzzled, in order not to graze from other people's fields. 1
Ohr ha'Chayim: They were able to carry much.
Ha'Emek Davar #1: They were tall and beautiful.
Ha'Emek Davar #2: They muzzled themselves and would not eat others' property, like the donkey of R. Pinchas ben Ya'ir (Chulin 7a).
Why did Eliezer need to take ten camels?
Hadar Zekenim, Oznayim la'Torah (on Pasuk 51): In order to transport the ten men
See Oznayim la'Torah there, who also proves that, (a) in the event that the family would not agree to the Shiduch, the men would testify to Avraham that Eliezer had done what he could to bring the Shiduch about, and (b) to prevent Eliezer from transgressing the laws of Yichud (being alone with Rivkah
What are "all the good (things) of his master" to which the Pasuk is referring?
Rashi, Targum Yonasan and Ramban #1: It refers to a Signed on a document in which Avraham gave everything that he owned to Yitzchak, 1 as an incentive to allow their daughter to marry him.
Seforno: Silver and golden vessels and clothes. 2
Rashbam: Important men belonging to Avraham's household. 3
Ramban #2: The Pasuk means to say that [Eliezer was able to take ten camels, because] all his master's assets [were under Eliezer's jurisdiction]. 4
Ramban #3: Eliezer took with him ten camels laden with all the best of Avraham's household. 5
Hadar Zekenim: Ten men of Avraham's children (i.e. Talmidim), for Birkas Erusin.
Presumably, this means that he would inherit it after his death - Refer to 25:5:1:2. See also Ramban.
To which the Torah refers later (in Pasuk 54).
As we learned earlier (in Pasuk 2).
Where was Aram Naharayim?
Rashi: Aram Naharayim lies between two rivers (the Pras and the Chidekel). 1
It was the country (in which Charan was situated and) from which Avraham stemmed (Berachos, 13a).
Why does it say "va'Yelach" in between "Vayikach" and "v'Chol Tuv Adono b'Yado"?
Seforno: What the Pasuk means is that before leaving with his master's camels, he obtained permission from him to do so.
Ha'Emek Davar: Even though Avraham's camels were working in the field, and it would have been easier to take (borrow or buy) camels from others, Eliezer specifically gathered them 1 , and took them to Avraham's house to load them.
Having just stated that Eliezer departed, why does it repeat "Vayakam Vayeilech"?
Oznayim la'Torah: Perhaps it is to hint that Eliezer had 'Kefitzas ha'Derech' 1
How could Avraham give everything to Yitzchak? One may not transfer inheritance, even from a bad son to a good son (Kesuvos 53a)!
Refer to 25:5:151:1,2.
QUESTIONS ON RASHI
Rashi writes that Avraham's camels were muzzled, lest they graze in others' fields. Why was this necessary? Were they inferior to the donkey of R. Pinchas ben Ya'ir, which refused to eat untithed food (Chulin 7a)?!
Bartenura: R. Pinchas ben Ya'ir's donkey refrained by itself, for it was special for the Tzadik to ride on. The camels were for loads. Perhaps the animal that Avraham rode on would refrain from Isur like R. Pinchas' donkey.
Mizrachi: When the damage is established (it will pass through others' fields), we do not rely on miracles, just like we do not rely on a Mitzvah to protect from a known danger.
Sifsei Chachamim: What borders Reshus ha'Rabim is Hefker, for the owners despair. Eliezer was a Chasid and did not want to benefit from others, even with a Heter.
Oznayim la'Torah #1: This was necessary to teach people to do likewise.
Oznayim la'Torah #2: Not to do so would have smacked of conceit (by acknowledging that he was a Tzadik to whom miracles occurred).
Oznayim la'Torah #3: Avraham was too modest to assume that his camels would refrain from eating other people's crops.