Many programs can create PDFs. Probably the most WYSIWYG is OpenOffice.org.

I don't know of anything that can edit PDFs. That said, if you're filling out PDF forms, the best thing would be for the PDFs to be created as forms to begin with, which are editable via Acrobat Reader. I forget if you can save them back out with the forms filled in, though. I know that I've been unable to in the past, but I want to say that it was because the PDF was flagged to prevent me from doing that rather than there being a technical limitation. I could easily be wrong.