You can create a PDF of any review form that you have permission to see. These don't have to be complete and signed; PDFs can be created when you can access the form. This means that an author filling out a form can get a PDF of a form that he or she has saved for later, or a manager can PDF a form that was submitted to them, but they haven't signed off on yet. Once a form is completed and signed, a PDF will include the details of when it was submitted and signed, along with any comments.
To create a PDF, navigate to a form, either through the Forms I need to do list or via one of the workflows you can access through the other three lists. Once you're viewing a form, either with completed/submitted questions or just draft answers, you'll see a Download as PDF under the Options menu on the right hand side. Click that button to initiate a document download where you can save that PDF to your computer.
You can then share these PDFs by any means you want - email, post to a share folder, store on your computer.