Hi,
Yes, the NOT(X) is equivalent to U3(pi,0,pi) as you point out. Thanks for catching it.
I appreciate your kind words. Thank you. While I show that the qubelet model boils down to the Bloch Sphere, my objective though is to convince the reader to see that manipulating qubits is more intuitive using qubelets rather than juggling with the Bloch Sphere. This becomes especially more acute when you are working with multiple qubits.