Is a great and reliable car if is care.
Yes. The things that you said are correct.
You need to check the oil levels every 1-2 refuel, look compression issues, and make a mod that consists in disconnect the oil injection pump that injects oil to the engine chamber, from the oil pan, and attach to a independent oil reservoir. And, now, you can put full synthetic oil in the normal carter, and in this new tank, mineral oil (like Idemitsu).
With this mod, if you forget to put oil, you only need to change apex seals in the better situation, and not breaking all engine.
If you don't make this mod, put mineral oil (mandatory for wankels. The semi and full synthetic makes a white paste inside the chamber).
The premix... I'm not a friend about this idea, but it works. Only that I think that it could obstruct fuel injectors.
And, here, in Spain, I know a person who had 300.000km with his rx8, without issues and not opening the engine. Following the Mazda owner's manual steps.