From memory, I think there's a 12 nautical mile limit that is accepted by everybody as a nation's territory. But many nations claim a much larger area of ocean outside their coastline - more like 200 nautical miles. That would be in international waters, so you could theoretically rule your own private artificial island if you wanted to. No, although the international law of the sea would apply. Correct. They wouldn't have to pay taxes. But they wouldn't be getting any government benefits either.
Several people have attempted to create countries on abandoned oil rigs, small islands indifferently claimed, etc. It's better not to get too rich. Being your own law, you have no protection from anyone else's.
there are certain international laws which all countries must follow. the international convention on torture for one, the international convention on slavery ect
It depends where you are and who is closest to you and the value. Likw someone here said, you wont get protection from a larger governing agency, so use this as a reference: Some would shoot you. Some would imprison you for life. Some would cook you and eat you. Some would hang you. etc.
