What exactly did the chief baker see?
Ramban #1 (citing Targum Onkelos) and Seforno: He saw that Yosef gave the butler a good interpretation, which he assumed he would also receive. 1
Rashbam: He saw that Yosef's interpretation was correct - because 'the truth is discernable'. 2
Rashi (on Pasuk 5), Targum Yonasan: He knew that Yosef's interpretation was correct, because he had dreamt the butler's interpretation together with his own dream. 3
Ramban #2: The chief baker belittled Yosef, assuming him to be incapable of interpreting dreams. And he had no intention of relating his dream to him, unless he saw that he offered the butler a plausible interpretation.
What is the significance of the word "Af" (which literally means anger) with which the chief baker opened his words?
Targum Yonasan: The chief baker did indeed speak to Yosef with anger. 1
The Midrash Rabah (19:2) writes that four began their words with the word "Af": the snake - in Bereishis, 3:1; the chief baker; the congregation of Korach (Dasan and Aviram - in Bamidbar 16:13 and Haman - in Esther, 5:12. And all four of them were destroyed with anger. It is not however, clear what he was angry about. See Oznayim la'Torah.
What exactly are "Salei Chori"?
Rashi and Rashbam: Wickerwork baskets full of little holes, 1 into which cake-merchants place their wares to sell.
Ramban (citing Rav Sa'adya Gaon) and Targum Yonasan: Baskets containing white (clean) bread. 2