Ive never had the oppurtunity to start one, but they run on a mixture of ether, alchol [sp?], and lub oil. The handle on the top adjusts the compression, kinda like the timing. And then there is the standard model airplane mixture control. I guess they're really torky compared ot glow engines and they can swing a larger prop.
I've seen the fourstrokes your talking about, although I havent owned one - my last RC motor was a YS Futaba . 45 and it was a screamer. I assume the four strokes have all ball bearings, and their lubed by the blowby from the piston. 4 stroke fuel is formulated a bit differently I think.