The moment of truth in the golf swing is when the club impacts the ball and using an impact bag will help you get the correct feeling of impact
Making mini swings with your elbows glued to your body will give you the correct sensation of the large torso muscles swinging the club, not the arms
On your takeaway, when your club is half way back the shaft should be parallel to the ground and the clubhead should be even with your hands, not inside or outside of your target line