Mooo,
The only thing that occurs to me is that you didn't get out of the range of the French ships, or pirates if you have Build 11 and they appear as well, and so you didn't get the map option. Did you still see the red ship figures on your "radar screen"? You can still be in range of the enemy ships even if you can't see them on that screen, however, possibly you can try sailing aound the island rather than directly out to sea, but I don't recall the French ships chasing me very far away from Oxbay when I was playing that part.
I'm uncertain how you ae working on other quests if you can't get away from Oxbay, but your reputation shouldn't be affected by doing one quest over another, Did you borrow money from a Loanshark and not pay it back? Or fail to deliver a cargo, or not pay your crew? these are the things that usually hit your rep. (That and killing people for fun, <img src="http://www.piratesahoy.com/forum/style_emoticons/<#EMO_DIR#>/dev.gif" style="vertical-align:middle" emoid=":d:" border="0" alt="dev.gif" /> )
Yes, if you have Build 11 or one of the modifications on the POTC modding site on the main PA page. The original game ends at a certain point and you have to start again , or not finish the main quest, if you want to keep on playing.
Let us know if you're still having trouble.