Is the frequency response graph obtained from the impulse response, the total characteristics of fundamental and all harmonics?
It will be the total characteristics of fundamental and all harmonics, but strictly speaking, the graph will not be the same for the frequency characteristics from the sweep and the frequency characteristics from the impulse response for the following reasons.
In the case of a sweep, for example, all the levels of harmonics such as 2kHz and 3kHz are summed for a fundamental of 1kHz, resulting in a level of 1kHz. Whereas in the case of an impulse response, the harmonic component of 1kHz is such that the 2nd distortion is added to 2kHz and 3rd distortion is added to 3kHz.
Similarly, a level of 1kHz is not the same graph because it is the sum of a fundamental wave of 1kHz plus a 2nd distortion of 500Hz, a 3rd distortion of 333Hz and a 4th distortion of 250Hz, etc.