The F&W festival has several different components:
- The different food & drink booths. You pay for whatever you want to buy.
- Eat to the Beat concerts. Included with park admission.
- Culinary demonstrations & beverage seminars. Fairly inexpensive tickets.
- Separate events like special meals, last year's Burger Block Party, etc. More expensive tickets than the demos, cost varies by event.
- Probably something else I've forgotten about.
The World Showcase does get very crowded on the weekends, and during the evenings, but there's generally not a huge impact on ride lines in Future World. Most of the locals showing up for the festival aren't coming in to ride Spaceship Earth for the thousandth time.
Whether or not a 9-year-old would enjoy it depends on the kid. I wouldn't bother taking them to any of the demonstrations, seminars, or special events. As mentioned by a previous poster, there's no child price to omit the alcohol, they just don't get it. (Adults who don't drink are in the same boat, but hey.) The concerts aren't usually groups kids have heard of, but they could still have fun, I suppose. A lot of the food is stuff kids might think is "weird" - although if your kid has a palate that isn't geared to just chicken nuggets and pizza, they might enjoy some of it.