For lures, take as many as you can carry. You don't want to buy them in the islands as the price just about quadruple's. We now carry the pieces and parts to make our own. It ends up costing me about 50 cents per lure and while they may not be as pretty as the store bought ones, they still catch plenty of fish.
I can also confirm that the bigger the lure you use, the bigger the fish you catch. On board Dream Catcher, we generally won't keep anything over about 30 lbs. First off, we have a small fridge and we won't kill it if we can't use it all. Second, boarding a fish over 30 lbs while in a sea way is no small feat. We carry a gaff for such occasions, but in two years I have yet to use it. It may be because we have stairs down to the water level.
I would make sure that I have the best fillet knife I can get and a good old fashion sharpening stone. Several of the fish in the Bahamas (Queen Trigger, Spade Fish, Hogfish) have exceptionally tough skin and quickly dull the sharpest of blades.
As far as lure selection, your mileage will very. We have done really well with squid style lures, mostly in red or green colors. We have also had a lot of action on several "spoon" style lures as well. I am sure other lures work well, but these are our mainstay.
Make sure you have some kind of substantial pliers for dealing with the toothy fish that seem really common in the islands. Some of the barracuda we caught were over 7 feet in length and I think they could easily remove a finger or even an arm if you got too close.
Speaking of the toothy fishes, I recommend using steel leaders on every lure you tow. We only use 24 inch ones, because they are easier to store and even with these short one, we have never lost a lure due to teeth.
A good general purpose cutting knife is a must have too. Also, you should learn at least one good all purpose fishing knot for attaching your components. Trust me on this one, nothing is worse than hooking up a good fish and then watching a poorly tied knot give way and the fish escaping.
As far as technique, we run the windward rod about 200 feet back behind the boat and the leeward line back about 300 - 350 feet. Of course, we often have to adjust both of these as conditions change, but it gives a round about idea of what we do.
Another must have for us is a fish identification guide. It doesn't need to be elaborate, but some of the fish we caught might have just as easily been identified as space aliens if it wasn't for our handy dandy picture book. Ours also gives an indicator as to the food quality of each species, which for us has proved invaluable.
Ok, one last word on trolling. Don't be intimidated. It's a lot easier than you think. Just give it a whirl and see how you do. And I want 1/10 of what ever you catch for revealing my secrets. :)