R-word probably refers to "retard" which is a politically incorrect way of saying mentally disabled. The n-word certainly refers to "nigger" but that word is extremely unacceptable in every english speaking country. Im not sure at what age kids learn this word. People say "the n-word" in polite society because of the extreme negative connotations the word carries. In the US at least you will never see non-black people using the word in public. You will see some black people using the word but there is a debate in the black community about whether or not the the word should be used at all.

When something is contensious, some will always be ready to accuse for any use at all. It is a fact of human nature that we read into things issues that we expect to find, whether they are intended or not. So many activists use such tactics and bias knowingly, or unknowingly to create debate, controvosy, or for their own agendas. . In this case the n-word was indeed used for many years ina very negative way, far beyond simple description. It is entirely appropriate to object to being called it. It is just a shame that it is so polarised and thatrational reference to such words is not possible. . Still humans are far from rational in their workings. .