Teamboat Springs at Blizzard Beach is my family's list of top five favorite attractions in all of WDW! This is one of the few experiences at WDW where the entire family can see each other face-to-face while we're having a great time. For this, and Typhoon Lagoon's family raft ride Gangplank Falls, there is no minimum height requirement, so your son could enjoy the ride with you. However, each person on this ride must be able to sit independently. You son cannot sit on your lap during the ride, and he must be able to hold on himself.
Life jackets are always prudent in a water situation with a non-swimmer. However, you don't need to bring your own. Life jackets are available for use for free at Disney's water parks with a fully-refundable deposit. They are available in a variety of sizes to fit children and adults of all ages. If you click
HERE, you'll be taken to a video my daughters and I recently made at Typhoon Lagoon, the Disney life vests are shown in the video.
Hope you have a great trip.