IME it's best to either use a pot large enough that you don't have to break the noodles or, if that's not possible, wait until the noodles soften up just enough for you to twist them the rest of the way in with a pair of tongs. Broken spaghetti is a lot harder to keep on a fork, hence the spoon. Not overcooking the noodles is really important because no amount of sauce can cover up mushy spaghetti. When you bite into it there should be a little give before breaking through, the best way to figure this out is to just eat a noodle every now and then and take the spaghetti out of the water just slightly before you feel like it's good, it'll keep cooking for a little bit out of the water.

I've only heard about the oil bit recently and I still haven't heard the reasoning behind it, I've never done it.