What is Yakov's tent?
Ramban: It was separate from his wives' tents. 3 It was where the family ate.
According to Rashi, why did Lavan search Rachel's tent twice?
Rashi: Because he knew her to be particularly fidgety, and that, as such, she was the most likely person to have taken the Terafim.
Refer to 31:33:4:2.
Did the maidservants share one tent?
Ibn Ezra #1 (and so connotes Rashi): Yes.
Ramban: Surely they did not! When he visited one of his wives, the others should not be aware of his visit, due to modesty. 1
Ramban - to have Bi'ah in front of other people is Asur, as the Gemara states in Nidah (Daf 17a). (Surely all agree that they had separate quarters when Yakov was at home. However, when Yakov was fleeing, he feared lest Lavan come at any moment. Surely it was not a time for intimacy! Perhaps then he saw no need to make separate tents for them - PF.)
After it says that he did not find them in the maidservants' tent, why does it say "he went from Leah's tent to Rachel's tent"?
Rashbam and Ramban (citing the Ibn Ezra's second explanation) 1 : Due to the connection of this Pasuk to the following one, which discusses the dialogue between Lavan and Rachel, it found it convenient to set it this way (for brevity's sake). '
Rosh, Riva: Only Rachel's tent opened to Reshus ha'Rabim. One could enter the other tents only through hers. Lavan backtracked [and searched a second time in Rachel's tent because he suspected her].
Chizkuni: One can go from Leah's tent to the maidservants' tent only through Rachel's. He searched Rachel's again before searching the maidservants' tent.
Tosfos ha'Shalem (7, from Bereishis Rabah 74:4): Rachel had a tent in Yakov's tent, and her own tent. Lavan first searched Yakov's tent, then tents of mothers with the most children, so Rachel was last, and at the end, he searched her tent in Yakov's tent.
Ibn Ezra holds that the Torah concludes with the tent of Rachel, since that was where the Terafim were.
רש"י: באהל יעקב - הוא אהל רחל: אם כך, למה ממשיך הפסוק "ויבא באהל רחל"?
גור אריה: אחר שיצא מאהל לאה, חזר לאהל רחל.
רש"י: באהל יעקב - הוא אהל רחל: מנין לרש"י לפרש כך?
גור אריה: מפשוטו של מקרא נראה שהוא חיפש תחילה אצל לאה, וקשה שרחל הייתה עיקרו של בית? אלא שאהל יעקב הוא אוהלה.
גור אריה: אין הכרח לפרש כרש"י, כי אפשר שאצל לבן הייתה לאה חשובה יותר. 1
לשיטתו מוסיף הגו"א לפרש שלא כתוב 'ויבא באוהל לאה ורחל' אלא "ויצא מאהל לאה ויבא באהל רחל" כדי לסמוך לרחל את "וימשש...את כל האוהל" כי הכיר בה שהיא משמשנית.