Would I be correct in assuming that the extra duels in the DLC aren't part of the current run categories?

They haven't touch the leaderboard since the DLC were released.

It was more confusion on my part, since it appeared you needed the DLC to do most of the campaign. Unless you're implying opening up IL leaderboards or something.

I was implying IL story deck, so first-hand Exodia would only really come into play on the duels that had Exodia available.

All DLC would be a) obsoleted every now and then, b) expensive as hell :D