"Free like OJ" refers to OJ Simpson's acquittal in his highly publicized mid-90's trial for murder. He got off with no jail time, therefore Pac is referring to OJ as a free man
Trick:A broad term for describing women who are either teases, hoes, or one of the above pretending to be the other. Calling a woman a trick shows you are not impressed/convinced by their shit.
"Being a young African American male, it is a necessity to me to carry firearms to defend myself because my demographic group is so at risk as victims of violent crime."
2pac says to tell his people he's a rida(he's down for watever) he's a outlaw. He says "nobody cries when we die, we outlawz let me ride" basically let him go in peace because life goes on