Ya bump on this thread. I'm comparatively new to AH (18 months or so) and have found the dueling league to be the most enjoyable experience I've found so far in this game.
JDog, the dueling ladder is actually the DFC (aka Dog Fighting Club). DFC isn't a squad, so it doesn't impact your existing affiliations. Just let Ink know you want in and he'll set you up for access to the private forum and add you to (the bottom of!) the ladder. Then it's up to you to whom and how often you challenge.