Are the acts of reviling, praying for scandal and revenge, and exposing the secrets of drug and human organ traffickers considered backbiting (namimah) or slander (gheebah), or do they fall under "whoever tracks the nakedness of his brother"?

It is not permissible to accuse anyone of serious charges without conclusive evidence. If you are certain of the truth of what you say, then you must inform the competent authorities to punish them, warn against them, and explain their danger to people to stop their evil. Your mentioning of their corruptions in this manner is permissible and rewarded, because it is not among the forbidden backbiting.