Well, it is pretty much required by the Open Gaming License that any rules content be open, so yes, pretty much all the text except for company names and such are OGC.
To Arcane Runes Press, you're not the first to comment that offering prizes might bias the reviewers. The issue of the time constraint is valid, but we had to limit the contest somehow, and we wanted to get some reviews up because, as far as I know, staff reviewers at ENWorld still aren't supposed to review ENPub products. We wanted to offer potential buyers the ability to see what others had to say. I thought this would be more fair than having people buy it blind, so I think your suggestion of bias is a little unfair, since we would have awarded a prize even to someone who gave us a 1.
However, I am eager to 'clear my name.' If you were already a little interested in the book, I could send you a comp copy now, and if you think it genuinely deserves a 4 or a 5, you could buy a copy for yourself. Would that be fair?