Bearing in mind that Eliezer was an Eved Kena'ani, why did Rivkah call him "Adoni"?
Oznayim la'Torah: She prophesied without realizing it, inasmuch as due to the Chesed that Eliezer performed with Yitzchak, by bringing him Rivkah as a wife, Avraham set him free. 1
As explained in Pirkei d'R. Eliezer, chap.16. (The question is not so clear. It was not blatant that he is a slave. It is proper that children show respect to older people (Eliezer fought for Avraham 65 years ago), especially according to the opinion that she was only three years old!
Why did she hold the jug while he drank? A woman may not serve a man!
Teshuvas Shevet Sofer (OC 40): They had not yet decreed that a woman may not serve a man. Had she given the jug to him, he would be obligated to give to his camels before he himself drank.
Toras Moshe (21): One who takes (borrows) a flask from a minor may not return it to him, for a minor does not guard property properly (Bava Basra 88a). 1
I.e. had she given it to him, he would need to follow her to her house to return the jug to her father (a toil, and perhaps they would be alone together on the way). She had no idea that he and the other men would want to go to her house! (PF)