Was Yakov really obligated to got such lengths to guard Lavan's flocks?
Bava Netzi'a, 93b: 'How far is a Shomer Sachar (somone who guards for payment) obligated to guard? To the point of 'I was consumed by the heat in the day and by frost in the night!' 1
See Torah Temimah, note 7 who elaborates.
Why did Yakov say "va'Yom Achalani Chorev... va'Tidar Shenasi me'Einai"?
Tosfos ha'Shalem (1,2): I did not sleep normally, nor take refuge from the sun in cracks in rocks, like other Shomerim. How could you suspect me of theft?!
רש"י: שנתי - לשון שינה: למה לא כתוב 'שינתי' ביו"ד?
גור אריה: דרך היו"ד להיות נופלת.