Why did Yakov not remove the stone before Rachel arrived?
Seforno: In order not to cause others a loss - should the three shepherds water their flock before the other local shepherds arrived.
What do we learn from the fact that the Torah writes "Vayagel" (and not 'Vayegalel')?
Tosfos ha'Shalem (6, citing Maharam bar Baruch): This is like "va'Yagel Kevodi", to teach that Ru'ach ha'Kodesh came upon him.
Why does the Pasuk repeat "Achi Imo" three times?
Or ha'Chayim #1: To teach us that everything that Yakov did was only because Lavan was his mother's brother, and that it was performed in honor of his mother 1 and not for any other motive.
Or ha'Chayim #2: To remove any suspicion that his actions were based on infatuation with the beautiful Rachel. Indeed, in order to avoid this, he made the point verbally with each action.
Tosfos ha'Shalem (8): Even though Lavan was a Rasha, his daughter was [righteous,] like his sister. Even though it was Lavan's flock, it was like his sister's (it did not eat from theft). Lavan had other flocks, Yakov gave to drink only what Rachel tended.
Oznayim la'Torah: In keeping with the Gemara in Kidushin 31b - that when, upon requesting 'Send me!', 'Hurry me!' or 'Release me!' one adds 'on account of my father!', one is fulfilling the Mitzvah of Kibud Av - See Oznayim la'Torah.
Why does the Torah say nothing about Yakov drawing water from the well?
Targum Yonasan: No sooner had Yakov removed the stone, than the water began to flow automatically and rose to meet him, and it continued to flow for twenty years, as long as he lived in Charan.
רש"י: כזה שמעביר את הפקק מעל פי צלוחית: מנין לדרוש כך?
גור אריה: לא כתוב 'ויגלגל' אלא "ויגל", משמע שזה לשון גילוי- הסרת פקק החלון.
גור אריה: ריבוי האותיות מורה על ריבוי הפעולה, ולכן כשכתוב "ויגל" ולא 'ויגלגל' משמע שזו הייתה פעולה חסירה.