You may be analyzing too much. Truthfully, I recommend the semi-western forehand (thats what most tour players are using). Eastern backhand is good though.
In terms of shot mechanics, Your arm will never be completely straight, whether you like it or not. Secondly, do not TRY and bend your elbow, this will force your arm to finish your stroke too quickly. You want to hit OUT on the ball first, then follow through arcoss your body. If you intentionally bend your elbow you will never get this.
In fact, i would attempt to keep your arm straight when you bring it back therefore it will be straight when it comes forward. This will give you the most power on your shots. The only time you will see pros with noticably bent arms is when they are hitting a high ball!
Hopefully that helps. I am a USPTA pro and run the site TopspinSports