I do not know about why PDF is set as the default for that printer. I never saw an HP printer use PDF as a default language for the printer.
Did you download and install the HP drivers for Linux? Here is the link to the site.
http://hplipopensource.com/hplip-web/index.html
I have two HP printers. Color Laserjet 2600n and PSC1410. I needed these updated drivers to make the printers work the best for Ubuntu Linux. When you run the file in the Terminal [instructions are given on the site], it should ask about which OS and printer you have, before you download the needed file. Then when you run the script, it will download everything that is needed and install the needed packages for you.
This may help, if you did not install the drivers. I found that the drivers included with Ubuntu 10.04 was not as good as the most up-to-date ones from that site.
The system shows the OS for SUSE 11.3 and 11.4, and you will have to page down the printer list a long way to get to your printer, after you select OfficeJet Pro as the type of printer. I do not see ArchLinux, but you should be able to use the driver from the parent OS like Debian, Ubuntu, SUSE, Fedora, etc., whatever it is. It shows the same version for the package as you listed, but so did Ubuntu, but for some reason when I installed the version from this site, it seemed to work better. Actually, I just realized that I am running an older version than is online, so I will be upgrading it myself.
IF you still have the problems, make sure you use the non-PDF language for your default printer language. HP's language or Postscript language is preferred.
As for CUPS, did you install CUPS-PDF from your package manager? That is my default way to print out PDF files, even from LibreOffice [most of the time].
As for the 2 pages per sheet, the orientation for the sheet should be landscape. If it is otherwise, then there is a problem.