Why did Lavan mention "Benosai" twice?
Rashi: Because Bilhah and Zilpah were also his daughters - from a concubine.
Why did Lavan decide to add Hashem to the list of witnesses?
Seforno: To warn Ya'akov that, in the event that he transgressed the covenant, he would be subject to Divine retribution.
Why did Lavan say "there is no man with us"? His brothers were with them!
Hadar Zekenim: They were relatives; there is no one here Kosher to testify.
Moshav Zekenim: He called his brothers 'dogs'. This is difficult.
What affliction of his daughters did Lavan warn about?
Rashi: Yakov may not deny them Onah (intimacy at the proper times).
Bechor Shor: He may not make them work too hard.
Tosfos ha'Shalem (5): He may not vex them in various ways.
Tosfos ha'Shalem (1): He warned against unnatural Bi'ah (in the anus).