There are many restaurants out on the main road( bay area boulevard) next to your hotel. Lupe Tortillas isn't the closest or even the best. You'll have plenty to choose from and won't have a problem. BJs Brewery (and restaurant) is good.
The Kemah Boardwalk is mostly a seafood restaurant area with some rides and midway type games (Skeeball , etc) on the channel going out to Galveston Bay. Gets VERY crowded on weekends, especially with good weather. I assume you're taking a cab because it is several miles from your hotel. The food is typical chain seafood fare (Joe's Crab Shack, etc.)