Yup, and I said that, chloroplasts are another, as I already said.
You're dancing around the point, which is that there certainly are cells which do not require seperate organelles, whether mitocondria or chloroplasts, to produce energy, for instance all procaryotes. Therefore your objection to the theory of a parasitic origin of mitochondria is not valid.
Of course it is - because whatever organism it was, already had to have a way to make energy to be alive. Mitochondria, like chloroplasts are not individual organisms any more than the the stomach or the lungs are individual organisms and not even evolutionists are stupid/dishonest enough to claim that stomachs and lungs were parasitic organisms.