How do I turn a Safari Webarchive file into a folder?
Is there any currently available software that can convert a Safari
  webarchive file into a more standard format?


If you are comfortable with command line, there is a tool textutil on Mac OS for converting webarchive file to txt, html, rtf, rtfd, doc, docx, wordml, or odt.

Example:
textutil -convert html /Users/USERNAME/NAME.webarchive



For converting webarchive file to pdf, try "Wondershare PDF Editor for Mac". http://www.wondershare.com/pdf/how-to-convert-webarchive-to-pdf.html