RE: Diesel?
Well, a quick look at those links didn't answer your questions for me, so maybe this'll help. (In the interest of full disclosure, I've never run a diesel, but I've read a lot about them).
Model diesels are basically the same as 2-stroke glow engines without a glow plug. Instead they have a threaded insert that can be used to adjust the compression ratio of the engine. The fuel is not the same as "diesel fuel" for trucks and buses. Like glow fuel, it's a mixture of a few things including oil and ether. And unlike glow fuel, you pretty much have to mix your own. The biggest drawback I hear is the smell of the fuel and exhaust, and the need to mix it up yourself.
I'm sure I'll be set straight if I messed up in my explanation of the details!
Phil