Common repairs:
Mazda made the 8 incredibly easy to work on, and insanely expensive to get someone else to work on. Coils are 20 minutes for the untrained with a 10mm socket wrench and $140 in parts, $300 is the lowest I have seen a dealer charge, $500-$700 is common. Plugs are $80 in parts and 10 minutes for the untrained with a plug socket and a few ratchet extensions. Dealers are $300-$500. Plug wires are $60, and less than 5 minutes to change, no tools needed (though removing the intake makes it easier) A full brake job at a dealer, or just about any other shop, will run you $1200+, $500 or less doing it yourself. Even other stuff like suspension components (struts, springs, sway bars, end links) are really easy to remove and install compared to other cars. Engine components are too, like the water pump, thermostat, alternator, air pump. If you need something replaced, there is probably already a DIY on here, and tons of friendly advice to help you along the way. Most of us don't need much of an excuse to find a reason to wrench on an 8. We just love it. Beer is a common currency for help

Cooling Cooling Cooling!
In case it hasn't been clear enough yet, you CAN NOT let your RX-8 overheat. Overheating a piston engine doesn't automatically mean the engine is damaged. Usually because the needle starts moving before it gets to critical temps. And even then, the temps you can let it get to are usually greater, because of the more even heat distribution in a piston engine. None of this applies to rotaries. If the temp needle in your RX-8 starts to move, it's already at critical temps!. And this is just the water temp. The uneven heat distribution means that there are parts of your engine that are A LOT hotter than this. Even a SINGLE overheating event can damage your engine. Yes, 1 time overheating CAN destroy your engine. It doesn't mean that it will. The danger from overheating is that the temperature differences in the engine block start to warp the gaps between the irons and housings. This creates a sealing problem and allows coolant and oil into the engine. Often it damages the coolant seals and oil control rings as well, compounding the problem. Once this happens, there is no repair. Even the engine parts that are there are probably not re-usable. You can run the engine still, due to the rotary's remarkable ability to run even if it's technically damaged beyond repair, but the uneven wear patterns and coolant present will accelerate internal damage further and further.

You can reach this through having too low of a coolant level, a thermostat failure (often strikes without warning), coolant bottle cap failure, coolant bottle failure, coolant hose failure, or sediment clog in the cooling system (sediment is slow rust that gets stripped from stuff and left in the radiator, hose junctions, etc...)

It is in your best interest to get a water temp gauge. Either a physical one hooked up, or an ODB2 one. Many methods to go about this. You can't rely on the OEM water temp gauge here!

If you do see the needle start moving, or your added temperature gauge shows you headed toward danger, immediately pull over and let the engine idle. DO NOT shut off the engine! Shutting off the engine will allow the temperature to spike even further since there is no coolant running through the block if the engine is off. While it is idling, pop the hood, check for coolant spray from the overflow, check the coolant level if you can (often hard to see), look for coolant leaks. If you lost alot of coolant, carefully depressurize the coolant bottle and add water/coolant The introduction of the cold (ambient) coolant will be immediately helpful