1) Who was Nevayot's sister? What kind of character was she? Did Esav take her as a wife? If yes, then why? 2) Why was Izchak told not to go to Khanaan to look for a wife there?

Nevayot's sister is Machalat (both children of Yishmael) who was taken by Esav (Breishit 28, 9) when he saw that Yitzchak, his father, didn't want his children taking Canaanite wives (ibid, 8) because they were pagans and immoral (Vayikra 18, 3 and Dvarim 12, 30-31). In addition, their families are around to influence the grandchildren. There are different midrashim regarding her, for she is also called Basmat (Breishit 36, 3), for she sacrificed incense to the idols, but others say she was later called Machalat for Esav's sins were forgiven when he married her.