Adobe have a server product snappily titled "Adobe LiveCycle Rights Management EC2" which aims to provide an audit trail of who has opened and printed a document, and can even revoke reading rights to a PDF file remotely. It's designed to keep confidential documents safe, so it may or may not apply to your situation.
As discussed in "is there a simple way to make a PDF call home?", users generally don't trust PDFs that they suspect to be phoning home, and the technical hurdles of doing it with 'vanilla' PDFs in a wide range of readers don't make it viable:
However, you won't be able to have this automatically run when the
hook for this. It will allow you to run this check automatically when
the document is saved, closed or printed but not when it is opened
(probably for security reasons). Alternatively, you could have this
check be user-initiated by placing a link/button on the first page of
All of this assumes you're using Acrobat as your reader.
Speaking personally, I haven't had Acrobat installed on my computer for about five years, and know many who avoid it because PDF readers are built into many OSes now. (I use Preview on the Mac.)
Also see "Do PDFs have the ability to phone home" on Super User, which confirms that PDFs don't have the ability to 'phone home' automatically by default without any user intervention at all, except through scripted vulnerabilities that only affect certain PDF readers.
In short, unless you're prepared to use (and pay for) rights management software, and force people who wish to read the PDFs into using a specific reader and following a given set of instructions to open the file, tracking opens and pageviews is difficult or impossible. Unfortunately, that makes it unreliable to the point where it's not likely to prove a useful metric of reader engagement.
If you're looking for some data to provide to partners who place adverts in the PDF, I would suggest:
1. Offering number of downloads per issue.
2. Offering them a tagged link in any PDF ads they place so they can track click-through.