New To Adobe, need help picking the right product

A small presecutor's office uses software that generates legal documents in PDF's. Five users in that office need the ability to edit the PDF's and add a signature (jpg, bmp, tif etc.).

The app generates pdfs that are formatted perfectly but once they open them in Word, the formatting isn't always correct.

What Adobe product do they need to be able to edit the pdf's and also insert a signature?

Any and all help appreciated!