How do you use honorifics in Japanese?

I know that "-san" is just to show respect, but I'm sort of confused about the others. "-Dono" is used for "sir,""-chan" is used for younger and familiar girls, likewise for "-kun" but for boys. I believe "-sama" is for people with high social standing than you and "-sempai" is used for someone with more experience than oneself. But in animes, people address people slightly differently. I heard in "Bleach" that Yuzu addresses her older brother, Ichigo, with "onii-chan" and her sister calls him "ichi-nii." In "Ouran High School Host Club,"Kyoya Otori addresses a girl "Renge-kun." This is confusing so can someone explain it to me in detail as to why they do this. And a quick question: Even if they don't have a higher social standing than you, can you call someone special to you "-sama"?