@ozski I work with lots of skiers at your level so your questions are all very good but there is no way to process everything you are asking on your hardest pass. Posture and lean angle are the most common mistakes i see when skiers are trying to break into shoreline, the next speed or the next line length. As the speed increases or the line shortens more leverage is required in order to create the same amount of space as the pass before. Space is created by edge angle of the ski...the more its rolled over the more space you will have. This is where posture comes into play. A stacked posture will allow you to apply or increase edge angle easier. A broken posture will let you pull harder but more then likely at some point the boat will flatten your ski out more (usually right at the wake) and take away all the angle you have generated out of the ball resulting in a poor line and running right at the ball.
So i will answer a few of your questions otherwise focus on the above and the rest should take care of itself:
Set up your ski to the factory recommendations.
Try to match the boat's speed as you turn in the gate and don't get too caught up in how wide you are.