As an RX-7 owner for many years (and recently an MZ3GT owner

), I thought I would chime in and clear up a few myths:
Yes, they do inject oil but in minute amounts - you might use a half quart every few thousand miles - by no means a pollution issue.
Yes, they do run very hot (1800 to 2000 degrees) and that is normal for this car. However, if you run them hotter than this, it can cause o-ring issues (not apex seals) - the rings are rubber and will turn as hard a rock if overheated. Hardened (and leaky o-rings) is not normal and is usually caused by poor maintenance, ie; vac leaks that cause a lean condition and thereby causing the engine to run too hot. Don't overheat a rotory and they will typically out live a boinger.
Gas milage is bad due to the design of the engine - wasted spark is the term sometimes used meaning the engine will actually not burn off all the fuel through the combustion cycle - this is where the pollution issue comes from and why the early rotaries had 3 catalatic converters. The RX-8 solves the issue to some extent by redesigning the porting. the RX-7's were brutal on gas - in the low teens for gas milage unless they were well tuned.
The biggest advantage to a rotory is the small displacement to HP ratio - smaller, light weight 1.1 and 1.3 litre engines that provided upwards of 200+ HP had a huge advantage over the piston - also the light weight, very nimble, and almost perfect 50/50 weight distribution. Plus the extremely flat torgue curv - meaning the car built power right up through the rev range rather than producing most of it's peaky power in the higher range as do most of the multi value piston engines (can you say HONDA?)