Beyond that, internal government policies and natural resources matter a great deal. 100 years ago, when all the world was market was agrarian, single family farms, government policies weren't as important. Today, if a dictator spends him money enriching his own coffers, rather then ensure a stable energy supply, the countries economy will suffer.
Absolutely! Beyond that, they also line their military coffers in order to stay in power. Since you can't eat guns, it presents a problem.
The Third World's main problem is education. Education leads to more efficient labor force, even when the jobs are not "white collar".