Your DC will take French 1 unless they test into a higher-level class. Their other classes will be in English with kids from any of the three language tracks. The language programs are not self-contained.
It's a large school, can be chaotic at times (but so are all middle schools). Homework is basically unfinished classwork.
I recommend doing more with French (even if it's just Duolingo, watching a French-language show, listening to music), otherwise the going will be slow, in terms of language acquisition. If you ever thought about taking up French, now is the time.