"This amplitude is then stored in a 1 x n array."
Close, but traditionally the data is stored in an N x C array, where N is the number of samples and C is the number of channels. For one channel this is the transpose of what you wrote.
"Is there a method of outputting the amplitudes that the microphone has received, which are stored in the array?"
Sure, once they are in MATLAB they are just numbers and you can display them or plot them.
"And if I am to apply a time delay, I would calculate the desired delay time, and then multiply it by the sampling frequency, and offset the output by this number of values?"
That is one method, that is valid to within 1/fs seconds. But sometimes a higher resolution is desired, and in that case other methods need to be used.
"I now need to work out how and where the amplitudes are stored"
Look at the lines
plotFFT = @(src, event) helper_continuous_fft(event.Data, src.Rate, hp);
hl = addlistener(s, 'DataAvailable', plotFFT);
This says that every time data is available, that plotFFT is to be called with parameters src and event, and that event.Data will have the actual data input.
"and output these to an audio drive"
