SSAT - Anywhere from 60 percentile and up. But probably need to be higher if you are from China.
TOEFL - Generally around 100 (if it is publicized in the admission website), and can be lower if you have other things going for you, i.e., teacher recommendations, extracurricular activities, etc.

兼顧學校學習和美高申請，在校成績會有影響，那學校成績主要關注哪些科目？需要達到多少分？
English, Math, Science, Arts, Music, PE (Sometimes the US schools will also look at Chinese grades). Cannot say how many points because the Chinese schools all have different standards. So 90 point at one school may mean something else at another school. But generally, would recommend your child to get around A, A-, B .