At 10 a kid is plenty old to carry their own personal gear - unless the kid is very small or weak. My son has been carrying his personal gear since he was 6! It isn't fair to the other kids to have to hump the youngest's gear. Having a kid carry his sleeping bag, pad, clothes and other personal items isn't that heavy. By watching weight, it should be around 10-15 lbs at most.

As for bags, you might look at REI at their entry level backpacking bags in synthetic. Most sport reasonable weight and come in 3 sizes as well. A 20* bag will cover most aspects.

As for backpacks? Make sure they try said packs on, and loaded during the test. Each kids body will be different in fitting <img src="/forums/images/graemlins/smile.gif" alt="" />