The rotax engine is extremely common in autogyros and other ultralights. I suggest you google some rotax user sites if you want more detail. But broadly they run on avgas or motor fuel (mogas). I put super in ours, and the price is whatever the local filling station charges, certainly a lot less than avgas. I had a couple of 20l canisters and just filled up on the way to the airfield.
The comment that you would have to be stupid to mishandle the controls on takeoff is sadly what a lot of experienced pilots think and why I would strongly recommend comprehensive insurance. The ones with enclosed canopies have a safety hammer to break your way out. I would not like to think what it is like hanging upside down with fuel dripping on you and the weight of the machine stopping you from opening the canopy. You better hope that there are some brave souls around to help you get out. The open ones in my very limited experience are very cold even in summer. I understand that the UK insists people do a lot of their initial training on these open types. The sensation is however exhilarating, in my opinion like riding a motor bike in the air, but really cold even with motor cycle protective gear on.