1)
Why does it specify a widow, orphan, convert and Oni?
1.
Radak: Since they are weak, be very careful with them not to oppress them monetarily or verbally. Malbim - this corresponds to Mishpat.
2)
What do we learn from "v'Ra'as Ish Es Achiv Al Tachshevu"?
1.
Radak: Do not think about your colleague's evil in your hearts 1 . Even thought is forbidden, and all the more so deed! Also, thought leads to deed. Even if he will not do a deed, it is forbidden - "Lo Sisna Es Achicha bi'Lvavecha" (Vayikra 19:17)!
1
Malbim: This corresponds to Chesed and mercy.
