Your list of questions is a wonderful spring board for what the space program and amateur radio together can provide to the children of this planet. And you, as others, have noted that the key stumbling block to children attaining advancing interest in space craft communications is the irregularity of expected signals. This needs to be addressed in several ways. The signal must be of a nature easily understood by the child and at the same time able to capture their imagination. It must be of reseaonable expected occurrence.
Nothing is better.
5-6th grade classes can learn to use computers not as internet push buttons but as information gathering tools to gather Keps and UTC times to personally calculate spacecraft position to receive live overhead pictures from a real inhabited space station all thru their own efforts. They can discover who they are and what they can be and do. And in between they can use the computer knowledge to print out their own visual passage predictions to show their parents on the lawn at night. There is math and geography and computers and physics, learning and communication, team work and visual beauty all wrapped up in one inspiring project. If your family has never used the computer sound card to receive these sstv pictures from space let me know and I will send you some that my son and I recieved when he was 10 yrs old.