The 'To-do' field is purely to put notes on things that need to be done by Content Editors on that page.
For example, an editor might add a note "Add section about dog biscuits". Later, an author might come along, see the note and add the section. I believe there is a report where you can see all the To-do notes in the CMS.
By 'latest post story' - do you mean you want to show the Content of the most recently added child page of a page?
You can do this, but it requires changes to your page class and template. Have a look at the tutorials first.