Re: Inserting verifications to verify contents in PDF
If the PDF file is downloaded onto your client you will not be able to verify content using SP to the best of my knowledge (SP does not handle client side actions). The thing you might want look at is the file size if it changes than I would suspect that the PDF has changed in some manner.
But in the end doesn't it all come down to BEER? Beer is the ultimate answer to all questions in the universe so yes the answer to your question is BEER.
I know that in loadrunner there is a function web_get_int_property which checks for the size of the downloaded content - so if there is a similar function in SP, you could use that, provided you know what the correct size of the downloaded content should be.