You shouldn’t be calling the_form in a hook, but rather placing acf_form() directly in your template where you want the form to appear.
http://www.advancedcustomfields.com/resources/acf_form/
Saving and continuing later, to be honest, there is nothing that will tell you how to do this that I know of. I just think it should be possible. It will probably take some research to find your answer. To display a post that has already been created you need to display you form on template where the post would normally be displayed. I would then check to see if the post is published or not and if it’s not then show the form to edit it. Alternately you might have the form hidden with a JavaScript action to show the form if the user clicks on an edit button or something like that. I don’t know all of the coding that would be necessary. You asked if it was possible, not how complex it might be.
You could start new topics with specific questions along the way.
