I can't answer the bifocals question, but my guess is "no." You might check a scuba supply store to see if they have special face masks that will accommodate glasses.
The food is quite good. It's served cafeteria style, but it's not an all you can eat buffet. It's a set meal with a few choices of entree and dessert.
Yes, they take pictures while you swim with the dolphin and then sell them too you at $16 a pop. It's very easy to spend over $100 on photos. If you have a family member who's a good photog (and has a telephoto lens!) you might be able to get some good shots, but he/she will not have the access the "official" photog does.