Have you installed Sane? It is required to operate a scanner. In addition to sane, you will need a back-end to support the scanner.
This is the driver for the printer -->
http://www.linuxprinting.org/show_pr...-OfficeJet_K80
I assume this is what you installed. I looked here -->
http://www.sane-project.org/ but I don't see the scanner for the K80 listed. Not surprising. I have a HP Scanjet G4010 and there is not a driver for it either. I have had it over one year, and still no driver.
As a work around to get the scanner working, I installed VirtualBox and a WinXP guest system. I run the scanner there, and copy the files to my linux system. VirtualBox is easy enough to install. Then I installed XP as a guest, once again easy enough ( if you have a copy of XP ). I installed the scanner in XP, so now my scanner works. Not the best solution, but until I can find a driver for the scanner, it will do.
I have never tried to get faxing to work, either in linux or on a XP guest. That I can not help with.