Regarding the specific question from your 10 yo: You’ll need to get from the Beach Club to Disney Hollywood Studios. You have three options. 1) Walk from BC to DHS, approximately 20 minutes depending on your pace. 2) Boat from the YC/BC dock to the DHS dock, also about 20 minutes plus up to 15 minutes or so waiting for the boat. The boat will stop at the Swan/Dolphin dock enroute. 3) Walk over to the Epcot International Gateway to catch the Skyliner, ride that to the Caribbean Beach Resort transfer station, switch to the DHS Skyliner to complete the trip. Probably slowest and the Skyliner may not be running between the IG and CBR early in the day when Epcot has not yet opened.
Walking is the most predictable, since you won’t be waiting for a boat or the Skyliner. Also once at DHS, you’ll have to deal with the entrance gate security, the entrance gate itself, and the walk through the theme park to get to the ROTR ride itself. It’s a fair hike to that area of the park, but I have no idea how long it might take an anxious and energetic 10 yo. We’re senior citizens and all our in-park walking is at a leisurely stroll. I walk quite a bit on my own, usually at about 17-18 minutes per mile pace, and my time estimates in the previous paragraph reflect that when I’ve walked the route on my own. DW never walks to DHS (we normally stay at the Boardwalk Villas) so the boat time reflects that experience (the boat from BW to DHS stops at YC/BC and S/D enroute, so lots of experience).