The chocobo racing was dead when I played it, I don't see why they are updating it over other things. In the Belly I tried, but the low percentages and junk items simply didn't make it worthwhile. You catch a fish and trade it to an npc. You get a tiny amount of gil, and a low (under 5% or even less) chance of getting an item. Most were worthless, but the ones that aren't were pop items for a level 20 fight in which you had another low percentage chance to get a decent item. I caught about a hundred fish trying for the latter, didn't get a single pop item to even try for the fight, and gave up in disgust. Never mind that it took me months to get fishing up to be able to catch the fish needed anyways.

As for a single player FFXI, go play FF 12, or .hack://G.U.