I've added a few more things to a sentence. I'd like you to check it.

I included another doubt.

1) In particular, we may be interested in two different types of two-week courses: one for students, whose level usually ranges from low intermediate to upper intermediate; and one for those Italian teachers (especially science, history, and arts teachers) who will have to teach their subject in English in two years' time and usually have a low intermediate knowledge of the language.
2) Why is the sentence "Write to me soon" possible whereas "As I wrote to you" is a mistake?