Except that, in that Kaywoodie, the point of the "carburetor" is apparently to cool your smoke. In the "pieces" Elbert mentions, one is supposed to fill the thing with smoke, uncover the carburetor, inhale deeply, and have the huge influx of air shove it all into one's lungs in one big hit-- as far as I understand, always resulting in a horrible, hacking cough lasting for several minutes.
As for Buroak's pipe, my guess is that it's one of those designs where, for the purposes of both cooking and filtering, there's a hollow chamber inside the body, surrounding the bowl (or else the draft hole would enter the bowl about halfway up the side), and that plug is for de-gunking said chamber, where tar and juices would collect. I have no idea what the shape is actually called, but I'd agree on "Bilbo."