Like the previous posters mentioned, go on the website and have a look.
However, my advice with your family would be Islands of Adventure...I think it is more geared towards kids and tweens, where Universal Studios is more geared towards adults and movie fans.
I would consider the meal plan, though. Look online to find info and menus, but if you plan on eating lunch and dinner, plus getting a couple of snacks, it very well may be worth it. Unlike the Disney plan, you can go through the line as many times as you want throughout the day, and you are not limited to just getting complete entrees. You can just get desserts, you can just get snacks/side... Also, unlike Disney, you don't have to get it for everyone in your family...so if one kid is a big eater, and one isn't, you only have to get one plan for the big eater.
Kids 9 and under are only $10. You'll pay almost that for one meal. Adults are $21, but again if you are doing lunch and dinner, and snacks, it is worth looking at.
The unlimited refill souvenir cups are separate, though, just like Disney...but they are only $9.