Calling the kid "half-breed" and making fun of his accent I don't think are super serious, though if it's done on a daily basis and with malice (and not just ribbing) then that's different. Bullying is serious and widespread but I think kids should be able to take some insults and ribbing, I mean, I think you're gonna have a real hard time in life if you can't..
The comments from those girls about wanting to see him die and then being glad he did are on a whole different level; just disgusting. Their parents are probably scum too. That kind of bullshit is ridiculous and should be punished.
It seems, though it could just be media blowing it out of proportion, that bullying these days is much more psychotic and over the line than it was in the past. It's almost like kids are taking the kind of abuse that is thrown around anonymously on the internet, like youtube comments, and using them IRL and on social media against people they don't like.
Aziz Ansari does a great bit about it. But occasional ribbing isn't the same as bullying. Basically bullying is behavior that is completely unacceptable in the adult world. Zero tolerance of it at work and while some of it might be allowed outside of work persistent harassment can have legal consequences. In school, for some reason, it just isn't treated the same and it is far more difficult to escape.
Lastly learning to deal with it in school doesn't real help with the real world as it doesn't manifest itself in the same ways. I don't think we have to worry about shielding kids too much from bullying, the "skills" to cope with it in school just aren't going to help you outside of school. More than likely you'll learn terrible coping mechanisms, like hiding your thoughts/feelings/opinions, instead of developing good ones.