If you want to eat at CityWalk you'd better do lunch there and grab something inside the park. You don't want to take chances on getting left out because the service was slow or the restaurant was packed. It's better to be safe than sorry. I would recommend Finnegan's since it's right there at the holding area.
You'll have 60-90 minutes to kill between the time the park closes and they let you out of the holding area. Plenty of time to catch dinner at Finnegan's. Get there early tho, plenty of other people have the same idea.