The park's new policy requires anyone age 15 or younger, and in the park after 4 p.m., to have an adult with them. That adult has to be someone who is at least 21 years old. The chaperone is required to be available by phone at all times and stay in the park through the duration of the visit.
Tote bags can also be great to bring, as long as you don't overfill them. Make sure your tote bag has a zipper on the top, so your belongings will be safe when you go on roller coasters. If you are going on multiple theme park trips locally in a short period of time, you may want to even keep this bag packed.
If you're planning on going on water rides at the park, you'll need to keep your phone and other valuables safe from water damage. Bringing a waterproof bag or putting your belongings in a Ziploc bag will ensure they don't get wet.
Helpful? Depends on what your looking to do. If you're going with small kids and are just going to do camp snoopy then at least 4 to 5 hours. If your doing the whole park it will probably take all day, especially if you go on a weekend.
Single strollers, double-seat strollers, wagons, wheelchairs, and electric convenience vehicles (ECVs) may be used during your visit to Worlds of Fun, and you are welcome to bring your own.