I thought to myself, bugger this, if i want to read a .pdf on my Mac, the sort that I'm using in iBooks, i really want the full experience in the iBooks Reader and not Preview and i don't want to read them in .pdf format on my iPad Mini either, so, i went and downloaded
calibre - Download for OS X which i did once before a long time ago, and back then couldn't seem to work it out, but now, i have just Batch Converted 5 50mb+ PDF's into ePub Format with Covers and now i can read them as if they are a book instead of a boring .pdf.
Calibre now works well and easy to use. I basically opened it up, then in the Menu bar, picked "Add Books" and added my 5 .pdf's, and then selected them all by Highlighting them, then back to the Menu Bar, and selected "Convert Books" and Bulk Convert, and went and wrote a couple posts in a forum and 10mins later it was done.
So this is another way to do it, and have them in a book format, which is so much better to read then a PDF