Need help in understanding some things about noise and dynamic range analysis.

1) We know THD (total harmonic distortion) and THD+N (THD+Noise), which is THD measured with transient noise ON in cadence. Am I correct?

2) For a given input frequency and amplitude, SINAD is equal to THD + N, provided the bandwidth for the noise measurement is the same for both (the Nyquist bandwidth). What is meant by Nyquist Bandwidth, max frequency? In a case of low pass filter, max freq is equal to cutoff freq?

3) For Dynamic range we use a formula

DR=20log(rms input @1% THD/rms of input ref noise)
Here this 1% THD can also be seen as -40dB THD.

Now the question is if I am measuring THD+N, then will it be correct to use that value to calculate dynamic range?
If yes, How? Because this measurement has noise contribution as well.
If No, what is correct way to calculate the dynamic range using THD 1% rms input and Input Ref Noise? Should I turn OFF the transient noise in the transient analysis for this?