Your n2a card probably has an app named Nook for Android. If not, it can be downloaded from the market. It should show your Nook library items and you should be able to open and archive them just as you do on the stock Nook. The differences are small.
I've got the Nook app on the n2a card and all my B&N books are listed (and accessible). It's the books that are already sideloaded onto my Nook that aren't listed on the n2a Nook app.
What I'm asking is if I have to copy or move all my Digital Edition books to the n2a card before they're accessible via the Nook app on the n2a card?
I hope that makes sense.