I like it plain. I used to make it pretty regularly when it was harder to find good ones, still do sometimes because one of the local milks is really fatty and the yogurt is tastier, plus I can make it more sour which I like.
I believe the 'greek' refers to the style - some of the water is extracted from it after it's made (centrifuged out?) so it's thicker.
There are 3-4 bacteria that eat the lactose making yogurt from the milk - one of them is 'bulgarian' the others are 'greek', same spot on the world map, which makes sense and I've found that all good yogurts have all of them.
Indeed it's very easy to make - you basically have to keep the milk in the temperature range where these bacteria thrive. Heating it up first changes something with the proteins in the milk (I think) making the conditions better for the bacteria. With unpasturized milk the high temperature also kills any bacteria that may be in there so that they don't compete with the ones you're trying to grow.
Then after it cools off a bit you put a little bit of yogurt in it and let them start multiplying.
I measure the temperature the same way my grandmother and mother did - put my pinky in it and I have to be able to keep it in there for 5 seconds, otherwise it's too hot and will kill off the bacteria I'm introducing. I like it more sour, though, if you let it cool more it will also work but may take longer to set and will be sweeter. It's an easy experimentation.
Then it's a matter of ensuring that it stays warm for number of hours and simply insulating the container works very well (wrapped in towels/blankets/sweaters). I have a 'yogurt maker' which is really a double-walled plastic jar with a very weak heating element inside. I can fit a 32oz glass jar in it and that's what I do. It usually takes 3-5 hours if I use a spoonful of chobani to start it, if you leave it too long it'll just be more sour (more time for the bacteria to eat the sugar in the milk) and it could separate out some of the water. I don't care so I've left it overnight or even for 16 hours when I've forgotten it - I enjoy it just as much :)
Oh, and I use about 1-2 teaspoons of yogurt for a 32oz jar of milk - I first stir it really well in a small amount of milk so that then it can mix well with the 32oz.