My kids are 12 and 14. My daughter is the youngest and my son the oldest. This will be their second cruise. It will be great for them to have kids around their own age.
You are going to love your first cruise experience. The kids clubs are the best way for the kids to make friends. I let the kids enjoy their friends and activities but required them to report in. Last time we had walkie talkies. This was the best way for the kids to keep in touch. We have a set of 4 that get a 5 mile range or greater. You can also use cell phones and laptops these days, though there is a really high rate per minute. I am a little more concerned this go around because he boat is more open. I plan on giving them a really good lecture about running around and acting up. I worry about them going overboard. But then I worry about everthing with it comes to their safety.
Keep in mind that you probably will not be in your room much. It is also best to eat meals either early or late. They do an awsome job of keeping the food full. Since it's spring break for most, their will be a ton of kids so expect lines for everything. The pool will be busy too. Just go against the grain, either sleep in or get room services, it also doesn't hurt to grab your food and bring it back to the room. We have a suite so there is seating on the balcony and a small sitting area inside. Understand that lounge chairs will be a hot item so if the weather holds up don't expect to get any for the whole family or in a good location.
Alcohol and soda are extra as well as the finer eateries. You can bring your own soda on board but not alcohol (though you can buy it cheap on the boat or at port by the bottle). Excursions will be your biggest expense. I tend not to prebook mine. They run specials on the boat. Get to know the boat within the first day or to then relax. Don't feel like you need to be at every activity either because by the last day or two you will be worn out.
I know that's a ton of info, but I think I covered most of it. Ask away.
Don't worry, you are going to have a blast!