A huge granite slab rises up behind the camp and on a clear night with a fullmoon the reflected light knocks you on your butt. All good things come to an end with the hike back to Tuolumne Camp. As I remember the longest hike is about 10 miles and as you have all day and don't have to make camp you can go at your leasure. If you can't get reservations at Tuolumne try for White Wolf. Do the same for the end of the trip and spend another night at Tuolumne or White Wolf.
Young kids do just fine.
Can't remember the age limit but you will know when they are old enough - you don't have to carry them anymore. All you carry is your clothes. We always had a cabin to ourselves. If you have less time try the hike down Yosemite Creek starting from Yosemite Creek Campground to the top of Yosemite Falls and then on to the valley floor. It is about 10 miles almost all down hill.