I've been a fan of cb2Bb for years. It's a magical application (not an App!) for quickly processing a BibTeX entry for any bibliographic reference. A quick note about a feature I've only recently discovered---as recent as today: extracting of a BibTeX reference from a PDF file itself.
What remains is to tweak the script "bib2pdf" that is part of this package, to include annotations in the printed PDF. I've done it, but it's enough of a hassle that I don't wish to go through the process again. Mainly, I need to understand BibTeX better.
I processed a folder full of PDFs in about 2 minutes into a PDF listing. Quality was an issue. Again, no annotations and no abstracts. This is doable. Certainly it is a time saver.
This program works on Windoze and I have had it installed, but with lousy results on a mac.