It's different at every restaurant... not every restaurant is Disney owned...
Here's a few I remember...
Drinks:
Tutto Italia - coffee not included (really weird, but that's what they said in 2008... I complained... hopefully it changed, probably not).
Le Cellier - virgin frozen drinks included.
50s Prime Time, Sci Fi Diner, Whispering Canyon -- Milkshakes included as drink. I highly recommend the 50s milkshakes!
Signature Restaurants -- I think every signature restaurant included coffee or a specialty coffee (cappucino, expresso, etc.) in addition to a regular drink. I like coffee with dessert but not earlier in the meal.
Many restaurants have "Sides". On the deluxe
DDP, these were included at Flying Fish Cafe and Brown Derby. We surely didn't need anything extra to eat after appetizers... but I just wanted to try something.
California Grill -- there are 2 sushi appetizers not included. but the others are fine.
Fantasmic Package -- if you get the package either by paying out of pocket or using the DDP, appetizers are included even if not on the deluxe DDP. True at Mama Melrose and Brown Derby when we were there.