comebackshane: That triangular opening in the second picture is the mouthpiece (the wider of the two). There's no more to it. You close it with your mouth and blow onto the edge. The principle is today emplyed on reet flutes such as the ney and kawala. It takes a little bit of practice to get it to sound.
The hole spacing is borrowed from the kawala as well, it is about 2/12, 3, 4, 5, 6, and 7/12 from the distal end. From there it's fine tuning. Since hole size and shape and wall thickness contribute to the pitch besides the hole position, there's no exact calculating the spacing. Tuning is done from the lowest hole upward, sometimes it takes two passes.
On this particular flute, the fact that the bone flares open wider in the last two inches made my lowest two holes quite a bit too low, so I had to enlarge them.
watch out, you can always raise the pitch of any hole by widening it, lowering the pitch is not as easy. start out with small holes no more than a third of the inner diameter of the flute.
