I wouldn't cancel your plans based on red tide, it's super variable even day to day. When we were in Rosemary at end of Sept I had 5 people total, only 3 of the 5 noticed the effect one day of the 7 we were there. One day it made us cough and itchy eyes but by the next day it was gone. No dead fish though, which agreed would be gross. However, one person in our party is an asthmatic and it affected her strongly and for days after. I would be hesitant if any of your kiddos have breathing issues, but otherwise would still go.
Places to eat, we love Fish Out of Water in Watercolor. The food trucks in Seaside are fun, as well as the Great Southern Cafe. Also George's in Alys Beach, but that's a bit farther drive from where you will be staying. Real good place with the kids though, very casual.