A tax right now could most likely hurt the economy. Since developing countries are still focusing on the planning of their land, and futures, and building up, they spend their money to improve. Developing countries tend to have less money than developed countries, so a tax would not be wise.
Yes, the Kyoto Protocol is correct in exempting developing countries. Exempting the developing countries allows them to develop at a reasonable rate. If they had binding targets under the Kyoto Protocol, it would severely limit their ability to develop into an industrialized country. These developed countries are still commited to reducing emissions, just not as much as developed countries.
Yes, the Kyoto Protocol is justified in exempting developing countries. Developing countries should be focused on their basic needs, such as food and shelter, and basic medical care for their people. Concerns about climate change are a luxury that these countries do not have. The developed countries that are rich can make more modifications which will compensate for the developed countries.
Underdeveloped countries produce a great deal of GHG on their own. It is not just fully developed countries that have industries giving off emissions. Though underdeveloped countries do have lower emissions, they will eventually reach the same point as the most prominent industries around the world. All countries need to be treated the same.