Sounds like your living by the past. Iv'e never really been interested in history, but regarding racism I certainly know my limits. It seems you take this matter very seriously, an that's fine. but it's not me.
If I saw a white guy dressed up as TuPac, which I saw recently. I really wouldn't relate it to disrespect, neither did many people of colour, as I have witnessed it, they found it quite funny, especially when he was trying to rap like him. As we know it's about context. If I saw a white guy dressed as a person of color with slave clothes on, it would be a step to far.
You have to see things in context, you said you don't mind hearing racist jokes? All the white and black teenage gangsters call each other the N word, are they being racist to each other, I very much doubt it.