Seeing as one may not afflict any fellow-Jew, why does the Torah mention specifically a widow and an orphan?
Rashi and Rashbam: Because, on account of their vulnerability, people tend to take advantage of them. 1
Why does the Pasuk add the word "Kol Almanah ... "?
Ramban: To incorporate in the prohibition a widow who is wealthy - because her tears too, flow easily and she is in a constant state of distres.
What are the connotations of "Lo Se'anun"?
Rashbam and Targum Yonasan: It means "Do not torment ... ". 1
Rashbam: Like "Lema'an Anoso be'Sivlosam", in in Sh'mos, 1:11.
Why does the Torah begin (here) and end (in Pasuk 23) in the plural, and speak in the singular in Pasuk 22)?
Oznayim la'Torah: It is referring to an individual who oppresses a Yasom or an Almanah, but includes Beis-Din