I'll take a stab at a couple of these. For AAdvantage dining you do have to sign up separately than for NWA miles (even though both programs are run by the same company). You should register a different credit card to be sure there are no problems. Go the AAdvantage website and click to the page for earning miles, then the "more ways to earn miles" page. (I had trouble inserting a link here)

Similalrly for 1-800-flowers.com you should go through the AA website to ensure proper credit or go to www.aa.1800flowers.com. You'll see lots of choices for flower arrangements. As for the best deal? - who knows - pick an arrangement you like at a price you like.