How can i create fillable boxes from my scanned document?

Hi, i got a form from the custom at my country and the form has already created by our local government.  The form is A4, 4 pages of multi-copy so i need to use dot matrix printer to print up my application form after i inputed the text.  However, here i got an question.  How could i waive off the form which i scanned by PDF after i created the fillable boxes?

I just need the fillable boxes to allow me to input the text such as address or some of the details for application purpose then i could print it out from the form that is ready-made.

The other question, how could i create a form which is not A4, such as L: 15 cm, H: 7.5 cm?  I want to create and ready to print

Thanks