Re: tapered leader became a knotted leader...
You have some good information here and I want to present my thoughts. Every fly fisher finds a casting method that works for them. So when you hear conflicting information it doesn't mean anyone is wrong. They just have had different experiences.
A high back cast is very good but you don't want it to be extremely high. When you are casting you need to stand with your left foot forward and don't cast perfectly vertical. If you cast slightly to the side you can see your back cast better and it opens up your body. I disagree with those that suggest that you wait for the line to totally unwind behind you before making you froward cast. Your back or fore cast should begin when the line is in a "J" shape with a few feet that has not unrolled. When you see the "J" on your back cast that is the time to start your fore cast. You start the cast slowly, accelerate and abruptly stop your rod tip.
We all say you are casting the fly line but in fact what you are doing is unrolling the line. If you wait till the line is completely unrolled the line speed will drop and the line will start to fall. Our reaction time is not quick enough to wait for a straight line and then cast forward. A high back cast will help so that the line doesn't fall to the ground but it won't save your line speed.
Most wind knots are generally caused by the caster apply too much power on the stroke, especially the fore stroke. I did this for years until I learned that fly casting is not about strength. It is about technique and timing.