First, A country is legally obliged to follow the laws of all countries in which they do business. For legal purposes, "doing business" means actual physical operations in a country or knowingly and deliberately selling into a country. This is basic international law.
Second. That is not how import/export law works. I do not have time to explain how it applies, so Google it.
Third. Your second statement is correct.
Fourth. Your third statement is not correct. Apple can sue HTC in the U.S. b/c HTC does business in the U.S. Apple chose to pursue this case in the ITC b/c it is asignificantly faster way to achieve its business goals (namely, interfering with a competitor's sales of a product). Patent litigation through the court system is a very slow, years-long process, and could take long enough that Apple would be on the down-cycle again.
Second. That is not how import/export law works. I do not have time to explain how it applies, so Google it.
Third. Your second statement is correct.
Fourth. Your third statement is not correct. Apple can sue HTC in the U.S. b/c HTC does business in the U.S. Apple chose to pursue this case in the ITC b/c it is asignificantly faster way to achieve its business goals (namely, interfering with a competitor's sales of a product). Patent litigation through the court system is a very slow, years-long process, and could take long enough that Apple would be on the down-cycle again.