I recently got this game after playing Omega with some friends the other day; which I enjoyed it a lot.  I'm also getting Shadow of Omega Revised a bit later in the mail, but for now I'm playing BG&E.  But I have some questions, and  I might have more later on, so I'll lay the first couple I have here:

1) There are supposed to be two "Knowledge Reward" Event Encounter cards in this deck, correct?  I was just wondering since there are no other duplicates.

2) If I were to use the Witch's spin ability (-2 Combat on an enemy), and then I'd use the Knight's spin ability to unspin her, could I use her spin ability again to stack the effect (making it -4 combat on an enemy)?

I'll have more technical questions later on if I have anything that needs clearing up.  I'll check out the manuals online if I can find them and research there also.

You have it right on both accounts. There are 2 K. Rewards, and you most surely CAN use de knight that way. But don't stop there with a measly Witch. Think Lucanor and card advantage, or Millenium on a multiple advantage negation rampage.