The only things I have not yet seen in this thread that i still have questions about are
1. What exactly is Whitebeards condition, and how much longer will he last. (remember he was hooked up to medical gear. This may be part of the discussion between Whitebeard and Shanks). If the giant Whitebeard dies, what effects will it have on the story.
2. What is the source of the devils fruits. We see all these devils fruit powers, but not once have we seen a devil's fruit tree. No one has even mentioned the general vacinity of these fruit. Are they a product of the grand line, or can they come from anywhere. Are they natural, or did someone make them. I assume that there are multiples of each type of fruit, but we have yet to see any doubles of devil fruit powers. Does this mean that each power is really unique. Is there a fish fish devil's fruit, and does it allow the user to go in the water without being affected. Or is the fictional fish fish fruit the most useless devil's fruit because the person is affected by the water still.
I know, I know. Compound questions, but I have a tendency to ramble.
Also, I doubt the D means Don. I have a feeling there is more meaning to it just like there is more meaning to the idea of One Piece.