1)
Why did Avraham now look down (va'Yashkef) on Sedom?
1.
Rashbam: He wanted to know if indeed, there were ten Tzadikim, as he mentioned the day before, in which case Sedom would have been saved.
2.
Seforno: He looked down upon them with an evil eye, on account of their wickedness. 1
1
This conforms to Chazal, who maintain that the word "va'Yashkef" always means looking negatively. Refer to 18:16:1:1; refer to 18:16:1.1:1.