Can anything besides child abuse cause ptsd in a youngster?

Yes. Just about anything "horrible" can do it. (car accidents, fires, you name it). But, at the same time, who gets, and who does not get, ptsd, is a very very difficult thing to predict. It really depends on the kid.
Yes. Ptsd may result when a severe trauma happens to the child or from witnessing a severe trauma directly or indirectly (from the news media or accounts from others), especially if it happens to a parent or other significant person in the life of the child.