Regarding impulse responses for use with convolve:

Q.1  What is the best source for an impulse signal when taking
the impulse response of:

     a)  An electronic device (like a reverb unit, etc)?

     b)  An natural acoustic space (like a cave, concert hall,
         etc)?

Q.2  If an impulse signal x[n] is put into a system (electronic
device or natural acoustic space) and the measured (recorded)
output y[n] is the convolution of the impulse x[n] with the
response of the system, then doesn't y[n] contain the spectral
elements of the initial impulse x[n] as well?  Wouldn't another
signal p[n] when convolved with the y[n] impulse response also be
indirectly convolved with the initial impulse signal x[n]?

If this is so, wouldn't the resulting impulse response measurment
need some kind of de-convolution in order to seperate out the
excitation signal from the true impulse response of the system,
the later being what is kept and used to convolve other signals
with?

I am looking at some theory lit. on homomorphic filters for
cepstrum analysis and deconvolution and the above thoughts
occured to me.  There is an example of application to vocal
sounds where homomorphic processing is used to seperate out the
vocal cord excitation signal from the impulse response of the
vocal tract.  Isn't this the same situation as the one above? 
Anyone have any enlightning comments?