I think Shoreguy pretty much answered your questions except for the dining.
There are 2 main dining rooms with no sur charges. Of course added to that is the buffet. Also the Italian restaurant which requires reservations but has no sur charge and Endless Summer which is referred to as Mexican but I would call it closer to Spanish. There is no charge, reservations a must and one that should be tried. It is probably at the top of my list as favorite ship dining, especially when the price is nada.... For snacks, give the Blue Lagoon a try. They have great burgers, buffalo wings and a few others that are favorites of many. It is more like a small diner.
Sur charge restaurants: Ginzas which the name pretty much indicates what it is. They have a sushi bar as well as other Asian foods. There is a charge and the restaurant gets mixed reviews.
CAgney's the steak house usually is close to the top for many, It is just that, a steak house, very good with prices ranging from $20 to $30 per person. The $30 is for a whole lobster, surf and turf or extra large cut of steak.
Le Bistro, which, i beleive was the very first sur charge restaurant offed by any cruise line is French and well worth trying. Prices range from standard fare with several entree obtions, $15 per person, the specialty items like Chateaubriand for two will run $25 per person.
I think the last one that comes to mind is Soho, which is a small, very nice eatery similar to CAgney's but more romantic, slightly more contempory and a little less expensive.
Hope this helps some, enjoy the Star, we sure did.