We did exactly the same as you three years ago. Same time, same hotel, same questions. "The Brit's Guide" is essential and includes a lot of restaurant reviews. For more reviews of restaurants just do a search here. If your daughter is a fan of MacDonalds, there is one about 50 yards from the hotel. The foods very different to the UK. I'd recommend the steak and egg bagel.
Restaurants I've enjoyed include, The Olive Garden, Tony Roma's, Chilli's (who don't sell chilli !), Cafe Tutu Tango, Kobe, Prime time Cafe at MGM. If you're hungry, or picky eaters, go to the Golden Corral. The selection is amazing. My daughters were eating tuna salad and ice-cream for breakfast ! The hotel restaurant is OK for breakfast, and one of my daughters thought it was the best place to eat.
Pretty much, you can't go wrong eating out. Dress code is casual almost everywhere. You won't need any extra clothes for the evenings. That reminds me, the air conditioning units in the rooms are effective but noisy. We found them too loud to sleep with them on.
You are better off leaving evening adventures later in the holiday as your body-clock tells you to get up at about 5 o'clock to begin with.
I'd advise that you take a trip to Wal-Mart to pick up snacks and drinks to keep in the room. You might want to take some with you to the parks as the food is more expensive.
As a final piece of advise, keep some form of diary. I kept a note of where we'd been, and everybodies best and worst things about the day. You could post it here as advise to the next first-timer.