SnowWhite, they don't take 90 days out reservations at Universal. When you get to Citywalk, stop at the booth set up there. (It is just past the movie theater and near the Endangered Species store. It is in the middle of the walking area so you can't miss it.) They make reservations there for all the restuarants at IoA, Universal, and Citywalk (except for Emerils.) You won't need reservations any earlier than the day you are planning on eating there. Almost all of the time you can just get in as a walk-in.
As far as eating places for kids at Universal, Mel's drive in is fun for kids as is Monster Cafe and Animal Crackers.