You just asked a mouth full...
Well basically the market is being saturated with RX-8 that were not being properly maintained. Alot of new owners had no idea that they were buying a vehicle with a rotary engine or that they had to add oil on a regular basis. Other than that it is like any other car, you just have to maintain it properly. If you are looking at a specific car take it to Scott @ Mazsport (727) 530-9960, the will run a compression test on the motor and let you know if you have a lemon or a car worth buying. Talk to these guys also
Redirecting..., a few of them post on here and hang out with us from time to time. They are fairly knowledgeable and will help you get started.