How to save, display, allow user to enter information on editable fields and then save pdf to databa

Hi all,
   I know this is a loaded question but I figure I ask the community and see if someone has done this or has an insight on how to do this.

   We would like to be able to store PDF files that a user can download/open and then enter information in some editable fields.  Once that is done, we would like the user to save (submit button or other means) the information/PDF back to the database.

  Any ideas would be welcomed. 

Thanks for your help in advance.
Rolando