okay, what exactly does the glow plugs do?

i know im asking a lot of questions, but i got to know all this stuff

heats the fuel to fire the engine under compression.

The platinum on the glow plug causes a chemical reaction which ignites the fuel....blah blah....

It is similar to a "spark plug" on a lawn mower.

No, its more like a glow plug on a diesel, it gets hot with an igniter but once the fuel is first ignited it stays hot and keeps the cylinder firing. A spark plug needs a constant pulse of electricity.

Have a look at http://www.modeltechnics.com/glowplug/firepower.html to learn more about them. The test results on various engines/fuels give a good idea of why it's important to use the right heat range plug.