You need the applicant's consent, and since the principal applicant cannot apply for the notes, only the sponsor can. The sponsor has to include the signed consent form in the notes application.
What you might be thinking of is applying for the sponsor notes, which will not have anything useful (only up until the application us transferred form Mississauga to London Visa Office.
Principal applicant can order notes as long as he/she is present in Canada, with any legal status.
If you apply for notes for any other person but yourself or your children under 18, you must include a consent form.
You need to apply for case notes, electronic files, for the principal applicant indeed.
My passport was requested and sent at the end of September 2015. Is it worth it for me to order the notes (especially since I haven't heard back since then)? Or can you not order notes once your passport has been requested? Thanks!