A family of Microsoft word processing software products for creating web, email, and print documents.
Unless you want to roll up your sleeves and learn a whole lot about XML and content control mapping then you would probably want to hire someone to develop the "On selection" method. For the OnExit method, I am not aware a speific guide, but you could probably adapt the code in the following to suit your purposes:
http://gregmaxey.mvps.org/word_tip_pages/linked_content_control_dropdown_list.html