It's a frequent plot point from the beginning - a character's father is accused of r-pe. It's discussed in detail in chapter 13 but it comes up a fair bit through the book.
There is a place on the grounds of the Reformatory called "The Funhouse," where kids are taken to be beaten, whipped etc. It's first shown in chapter 12 but the theme of torture happens throughout the book.
There are repeated n-slurs in virtually every chapter - the book takes place in 1950/Jim Crow so the main characters (who are Black) are regularly called this and other names
Sort of - there is reference to kids listening to the Amos & Andy show on the radio, and a main character references his father forbidding him to listen because "those were white men playing Negroes, making Negroes look lazy and silly do white folks could laugh at them." (Quoted from chapter 11)