The pictures, angles, analysis and everything is great if you understand these concepts already but it's another thing to put this into practice. If you want to progress your serve into an effortless motion, I recommend either video analysis or a pro/coach that knows how to serve.
There really isn't a really good way to describe an effortless and powerful serve until experience it the proper technique. It really feels like your arm is a limp noodle and it's effortless.
In the beginning it will feel like you're bearly getting any power into your serves, but one day it will click and you can really begin to practice real serves. You just have to be mentally ready to practice through the days that your serve feels/looks like nothing. It's ok, though, in the beginning it's all about form, not power.
In tennis, if you goal is powerful strokes, it all comes down to racket head speed. The most efficient way to get power is really counter intuitive, more power in does not equal more power out. Think of your arm and racket as a whip, to get that whip to make that powerful snapping noise, you don't just muscle the whip, you have to work with the whip's flexiblilty to get it to snap. Think of your racket head as the tip of a whip, for power, your goal is to make that racket head produce that "snap" as if it's a whip. Pronation at the end of a serve is one key to the snap, but other areas of the service motion need to be there for it all to work effectively, otherwise you just end up injuring your wrist.