Is it right to talk about dynamic range on frequency domain?
the dynamic range is the difference between the largest and the smalles value of a quantity can asume, so yes, you can have a dynamic range for the magnitud of your frequency components, I'm not aware if there's another terminology when dealing with the frequency domain. One thing to consider is not only the dynamic range of your signals but also the dynamic range of the variables you'rr using to store it and to calculate the frequency response, altough in the frequency domain (and specially when working with dB) it's not a big issue.