have a vidi at the code in this post
. modifying it for your project would mostly involve removal of existing code and the addition of some code to sample and debounce switches.
there is a table of values for an eight bit sin wave, another table of values with the size of steps to be taken through the table to generate the frequencies for various notes. for each note to be played just look up the offset and let things run. there's some weird 24 bit, (8 bit integer + 16 bit fraction), fixed point arithmetic, but i hope it's not too hard to dope out.
instead of the sin wave, you could start with a sample of a real sound, modify the maths a bit and wind up with a bastard ocapiano or ocaroboe or something.
don't now what to tell you about a wind controller, but i've seen arduino projects that implement them. i guess another button would do to turn the breath on and off.
the hardware is really simple. a cap and a resistor for the low pass filter on the audio out and say, five buttons, (four hole ocarina, with breath button), with pullups enabled on the i/o lines.
"If I had known it was harmless, I would have killed it myself." - Phillip K. Dick, A Scanner Darkly