Hello, I'm new to the forum but I spent 10 years or so on property at Universal. I'm more familiar with the Studios than IOA, but here's my tips for eating venues:
Sit down restaurants: Basically, there are two. Lombard's Landing in San Francisco and Finnegan's in New York. Both are good, but Finnegan's is more like a truly Irish Bennegan's. Their appetizers are good, however. Lombard's is more upscale, and is the more expensive.
Counter service is extensive, and includes Boulangerie (sp, I never got that right) in Hollywood, Monster's Cafe in Production Central, Louie's in NY, Mel's Drive In in Production Central, Animal Crackers (open air) in the Fieval's area, Richter's Burgers in San Fran, and the International Food Bazzar in Amity. There are also multiple small carts or other spots to pick up snacks and munchies. I've never been to Monster's so I can't vouch for it. Of the burger places, I prefer Richter's to Mel's; the burgers are patties as opposed to the more compressed burgers of Mel's, the portions seem larger and they just taste better. Mel's has good shakes, though. Louie's has excellent pizza and tortellini. The IFB is more like a mall food court and the food is...accordingly. Boulangerie has huge sandwiches and deserts to die for.

Universal does not police bags that you bring in, so bringing in snacks is an option. Unless you get a locker, whatever you bring in, you lug with you, however. And if you get a locker, you have to hike to it to get what you want.
The few places I've been in IOA are as follows: Croissant Moon Bakery is pretty much IOA's Boulangerie. There's a stand right across from CM that sells fantastic funnel cakes. The Fire-Eater's Grill has fantastic boneless chicken zingers. I've actually bought the Zingers there and then walked over to the Enchanted Oak Tavern, which has fantastic ambiance. You feel like you're inside of a giant tree. I'm not too keen on the food there, however (hence the transporting of the food). They have a small full service bar as well inside the Tavern. Additionally, there's a fantastic slurpee-type place in Jurassic just over the bridge from Lost Continent that I adore. (I go for the blueberry or tangerine most often). They're non-alcoholic, but you can also get them with a shot of alcohol for those that prefer that.
Enjoy your trip!
Rose