I used the following to do the same thing on a form I did.
It is a text field that I am checking, and a subform that I am hiding if there is nothing entered in the field. The code is JavaScript.
if (path1.txtissue.rawValue == null){
path1.sfissue.presence = "hidden";
}
The code you would need is similar, except you are checking the value of a checkbox, and hiding the checkbox.
Don't forget to save the form as a dynamic form.
In order to 'economize the paper', you would need to have subforms set up properly for this to occur as desired. You would need a flowed subform and then the checkbox objects in a child sub form. When one of the child subforms is set to hidden, the flowed subform will re-calculate and move the subforms up automatically, creating your desired effect. This is why I hide the subform above and not the checkbox in the above snippet.
I hope that helps.
Words of warning: Since your form is 12 pages, adding dynamic content will slow the performance of the form.
Cheers,
Stone.