PDF files can contain metadata.  You could use a tool like iTextSharp to insert some after export, but this probably isn't the most useful way to convey the information - the PDF viewer needs to be able to display arbitrary metadata, but most applications support a fixed set of attributes in a fixed "properties" dialog.

You might consider making a cover page for each document that just lists out the metadata.  That's also something you could could do with iTextSharp.

You can include annotations, but I do not believe there is currently a way to include metadata when converting to a PDF.

Alex - If you need some PDP development assistance you are welcome to PM me at cprimmer@qfiche.com and we can have a conversation about your needs.

If you have time to write a program to parse XML files, one way is to export the documents as a briefcase, rename the briefcase to "tgz" (tar gzipped), uncompress it with a suitable tool (such as 7-zip), and then parse the XML files contained within.

If you need to export the entire volume, this can be done on Laserfiche Administration Console. After logging in to the repository as administrator and navigating to the volume, right click and choose Export. The exported volume should also be able to decompress, and then the XML files can be parsed.