You can order any of the entrees. The current menu on the Disney website doesn't list the steak and lobster tail combo, but in past it was dining plan eligible when it was on the menu. If you have the regular dining plan (1 TS, 1 QS, 1 snack per person) it does not include appetizers so any apps would be OOP. The entitlements of the dining plan do not change at the signature restaurants even when 2 credits per person are required. Also, you would have to pay OOP for any side dishes in the Side Dish, Accompaniments, or in Narcoossee's case, the Enhancements section of the menu since each of these items have a separate price point listed.