To the best of my knowledge the answer to these questions will depend on your particular state's regulations within the Department of Education.
My suggestion is to call the Director of your Special Education or Special Services Department and ask this question. If you do not know who this person is, then you might want to call the office of your son's school. Someone there can tell you who the Director is.
Also, usually the principals of the schools have some idea of the state regulations as well.
All that being said, I would be surprised if any state allows and IEP to be changed without the notification of parent or guardian. If you find that to be so in your state, please let us know.