Slippery slopes is usually a fallacious argument, decidedly so in this case where plenty of successful examples exists.
(1) https://en.wikipedia.org/wiki/R_v_Keegstra
(2) https://en.wikipedia.org/wiki/International_Covenant_on_Civi...
It means "intense dislike". If that is directed at an intrinsic property of a group of people, that's hate speech.
Example: black people as opposed to smokers.
No, because that's not an intrinsic property.
Hating people who take too long at the register isn't the same as viewing all redheads as inferior.