Hate is a strong word and racism cannot be defined quite so simply. Hate is not a prerequisite. Treating people differently whether intentionally or unintentionally would fall under racism be it because of presumed inheritable traits, abilities, or qualities.

True, just as recognizing differences without differential treatment is not racism.

How do you act/do racist things unintentionally?

My guess would be naturally avoiding someone/crossing the street if they were of another race.

But that's intentional, you made a choice to avoid them

If you avoid someone of another race who looks like a thug its no different from avoiding a thuggish looking person of your own race.

I think hate is a qualifier for racism.

Has to be right?

seems like it, if you indict an entire race on the actions of a few, then you might be racist

"Thug" is a term of endearment, a badge of honor, in the rap community therefore it is likely racist.