Best dinner spot on the beach is Kuyaba, for sure (in my opinion). The curried lentils app are so yummy and the lobster thermidor is out of this world...a MUST try, for SURE!!! They also serve a snapper sandwich on coco bread for lunch that will knock you on your knees!!! AMAZING!!! Kuyaba will come pick you up at any hotel and take you back as well...however I always just walk. I also like Angela's (upstairs from Bar b Barn)... the service can be hit or miss but the food is usually good. I am use to food taking a LONG time in Jamaica and I expect that, however I had a server there a few times who was just totally miserable, but have also had a great server too.
As for walking on the beach at night...be aware of your surroundings and walk at the waters edge. Don't engage in conversation with any vendors, ect. and keep a good pace and you will be fine. I have walked the beach in groups as well as alone at night and have always done fine. Just be smart.