Passing parameters via URL is very limited with PDF. You may be able to pass the page to open, but that's about it.
However, you can pass whatever you need using an FDF with the link to its base PDF. You would assemble an according FDFand open it in Acrobat/Reader, and it will pull in the base PDF and add the information into their according fields as well as run the specified JavaScripts.
Hope this can help.
Max Wyss.