Why does the Torah interrupt the dialogue between Lavan and Ya'akov with a description of Lavan's daughters?
Rashbam: To explain why of Lavan's two daughters, Ya'akov wanted the younger one. 1
How do we know that Ya'akov worked for Lavan during that period - since no mention of it was made until now?
Seforno: Refer to 29:14:1:1*
Ramban #1: It seems that, from the moment he encountered Rachel by the well, where the Torah records (in Pasuk 10) "and he watered Lavan's sheep", he continued to do so, to spare Rachel, whom he loved, the onus of doing so.
Ramban #2: Ya'akov initially stayed with him as a guest. However, after a month passed and Lavan saw that he was living off his kindness, he tricked him into working for him by flattering him. He told him that the man of ethics that he was, he would never agree to live off somebody else. He would therefore be bound to volunteer to work for him - not for nothing of course... .
What does it mean "Hachi Achi Atah va'Avadtani Chinam"?
Tosfos ha'Shalem (1, citing R. Efrayim): It is proper that you work for me for free, for we are brothers. However, I do not want this. 1
Bechor Shor: Since we are brothers, it is a greater evil if I do not pay you properly.
Tosfos ha'Shalem (5, citing R. Efrayim): Lavan craved money, even through theft. He should be thrilled that Yakov work for him for free! Rather, Lavan knew that a Shomer Chinam is exempt. He preferred to pay Yakov a little, to obligate him for what is stolen or lost.