2) "March 26, 2009", according to my calendar, is not "Monday".
3) If I were you, I won't write the note. I will go in with my daughter tomorrow morning and talk to the teacher and principal directly. (If you do so, be calm and do not threaten them with a lawsuit.)
4) What you want should be that school will ensure this will never happen again. (Not B promise not doing it again, as the promise is basically worthless for a minor.)