Definitely check out the cruise reviews for the Norwegian Sun. If there are any "mega-reviews" they may also include pictures, or links to same. Also check out port-reviews.com (also linked to this website) for information on the ports of call. The ship's shore excursions usually do cost more, but if you are new to cruising or to these ports (especially in Jamaica), I would still suggest going thru the cruise line's shore excursion office, at least for the longer excursions. Remember, if you are late back to the ship and have not gone ashore as part of the cruise line's shore excursions, you can miss the boat, literally - and the cost of catching up to your cruise is entirely up to you.
Have a wonderful time!