This brings up the question to me: How exactly did the Seven Armed Seas get contracted?
That would mean at some point (or several seperate points), all of them would have had to meet with the Gorosei, the Earthly equivalent of being knighted or contracted.
To me, the Seven Armed Seas are privateers. In exchange for following a few base rules, they're allowed a basic green card to whatever activities they see fit.
Sir Francis Drake (Who I think Oda used as the model for Mihawk, only… Drake was English, not Spanish) was perhaps one of the most famous. He was the first to circumnavigate the globe (Magellan died before he finished his journey), and was a brilliant captain and engineer. He was even said to have courted Queen Elizabeth at some point in time.
Now, historically, Teach was ALSO a privateer, though it wasn't well known. After seizing the "Queen Anne's Revenge", however, he became a pirate and began raiding the Mediterannean. His base was in the Bahamas, until Woodes Rogers (Does anyone else think this is where Oda got the name for Gol D. Roger?) drove him out of Nassau...
Or maybe Roger's modeled after John Cabot, the first European to discover North America (No, columbus discovered the Mediterannean Islands, sorry). Eh... someone needs to write into an SBS.
Anyway, the point is that the Seven Armed Seas are exactly like privateers: Hired by the Gorosei to raid certain enemy settlements (Pirate settlements, mostly). At some point, they all had to meet with the Gorosei to get their appointment.
You know, I dunno if you guys have thought of this, but Sukazuki reminds me of Nezumi with the hood up. Does anyone think they might be related? That would explain how Nezumi got Captain rank when he can't fight worth a lick.
As for Dragon vs. Luffy, Dragon is like Luffy's guardian angel. He has some ulterior motive for watching over Luffy. Perhaps Dragon made a promise to Luffy's Grandfather to keep him safe. A single man can't start a revolution, yanno... maybe Luffy's grandfather and Dragon worked together to create a new future for Odachii.
Also, assuming Dragon ate the Kaze Kaze no Mi, Luffy would have a helluva time trying to fight him. And no, he can't suck him in using Gomu Gomu no Fuusen... it would be just like when he tried to eat Croc: No good.
However, I do see Dragon meeting up with Luffy at Raftel, or perhaps earlier, at the Pirate's summit. It has to be fairly soon, because now that the Mugiwara have declared war on the WG, Luffy is no different from Dragon. He's a revolutionary.