When we lived in FL, we went to Universal a lot. It is absolutely worth paying extra for the speed pass. The lines can be very long, and you'll want to do as many rides as you can. Also, at Islands of Adventure, there are a couple water rides where you'll get very wet. We used to wear bathing suits and quick drying shorts when we went. DON"T wear heavy cotton shorts - takes forever to dry!
I've never been to Discovery Cove, so can't offer any comments.
Regarding food at the parks, it's ok. However, the restaurants do get really crowded. We used to leave the parks and head to the hotels for lunch. They aren't as crowded, since most people stay in the parks and only return at night. You can sit down and have a meal, and not be crushed. Each hotel has its own theme, and you can take the water taxi from City Walk, which is fun. The restaurants at City Walk are also a good option, but they do get more people at lunch, due to their proximity to the theme parks.
Have a fun trip