How did Leah know when Yakov returned home that evening, to guide him to her tent?
Why did Leah mention the fact that 'she had hired Yakov ... '? Why was it not immodest to talk like that?
Seforno: To reassure Yakov that she was not encroaching on her sister's rights, seeing as Rachel herself had agreed to allot that night to her. We see from this statement, indeed from the entire episode, that the Avos and the Imahos treated intimacy like Adam and Chavah before the sin - to have children in the service of Hashem and not for personal pleasure. Malbim
Why does the Torah omit the first 'Hei' in "ba'Laylah 'Hu' "?
Ohr ha'Chayim, Malbim: The "Hu" refers to Yakov, to inform us that he consented. Seforno
Tosfos ha'Shalem (6): Yakov would always go the tent over which he saw the Shechinah.
Tosfos ha'Shalem (2): This shows that Leah was not considered 'Chatzufah' (a wife who verbally requests to have Bi'ah, one of the nine Midos of despised relations).
He accepted her wholeheartedly - a large step forward from the 'hatred' that he previously bore her. (EC)
Why does it say "Sachor Secharticha"?
Tosfos ha'Shalem (4): the double expression hints that Yisachar, who was conceived that night, will engage in Torah and receive reward in this world and in the world to come.
Ohr ha'Chayim: I hired you for two matters - to spend the night with me, and to be intimate with me.
Ha'Emek Davar: This teaches that Yakov's intimacy was not for pleasure, Heaven forbid! Rather, he is obligated to his wives. Now he was obligated to Rachel, and Leah acquired this from her.
Why did Leah need to go to greet Yakov? Did she not trust Rachel to fulfill her word?
Ohr ha'Chayim #1: There was no Kinyan (acquisition) about this. If "Lachen" does not mean a Shevu'ah, she could retract. And even if it means a Shevu'ah, Rachel did not say 'this night', so she could trade it for another night.
Ohr ha'Chayim: Rachel would fell pain and jealousy if Yakov entered her tent, and left to be with Leah.