The first 2 questions remind me of the (fantastic) book I'm reading Doing Good Better. This is basically effective altruism.

This book argues that a dollar goes a lot farther in the third world. (Obviously.)

It also has a great story about how money spent on educational resources can have almost no effect while money spent on deworming (yes, worms) can greatly increase educational results. (Not so obvious.) This is a third world example but its fairly obvious the problems with US education aren't' resource or efficiency based.