Welcome from Okemos.
Although we are an open carry organization, many of us CC as well (sometimes we CC a backup, for example).
We encourage you to read the laws yourself so that you understand them, and not just take someone else's word for something that might get you in trouble. Having said that, the answers to your questions are:
Question A) The law states that you can CC in your vehicle if picking up or dropping off your child. You cannot CC in the building or elsewhere on the property. Here is the law:
MCL 28.425o Premises on which carrying concealed weapon or portable device that uses electro-muscular disruption technology prohibited;
(1) ...an individual licensed under this act to carry a concealed pistol...shall not carry a concealed pistol on the premises of any of the following:
(a) A school or school property except that a parent or legal guardian of a student of the school is not precluded from carrying a concealed pistol while in a vehicle on school property, if he or she is dropping the student off at the school or picking up the student from the school.
(4) As used in subsection (1), "premises" does not include parking areas of the places identified under subsection (1).
http://legislature.mi.gov/doc.aspx?mcl-28-425oQuestion B) no, if you are not carrying a concealed pistol, you do not have to tell law enforcement that you have a CPL and/or that you are not carrying. You are only required to disclose if you have a CPL and are carrying concealed. If you are carrying in your car, you must also disclose immediately.
Since you may be carrying openly on occasion, please read our FAQ when you get a chance. It answers a lot of questions regarding open carry.
http://www.miopencarry.org/faq