Watcher of mankind: Instead of praising God for his goodness shown in careful attention, Job accused God of hostile surveillance. This actually describes Satan's actions (Deuteronomy 32:10; Psalm 25:21; Proverbs 24:12; Job 1:7).
Why comes from the language of grief (see study note on 3:11–24).
Your target: See 6:4; Lamentations 3:12.