Quite a bit here that I’ve never even thought of. I’m wondering if a better route for you would be to self-host your own version of the full FiveFilters code then cron the various versions you need. This would give you more flexibility in the rss feeds you can pdf (wordpress lets you pull rss from all post,categories, tags, archives by adding ?feed=rss to the url. You could also merge feeds using Yahoo Pipes)
Some problems you might encounter for what you’re wanting to do are: rss feed limits and server memory to compile the pdf.
Sorry I can’t be of more help,