RE: Bitzenberger clamp
Not necessary to judge and adjust depth to the 1/8" recommendation as long as the quill is making full contact with the shaft. I clamp the feather so only the quill (rail) is exposed.
However, you must learn to control the run of the adhesive you are using as not to glue the feather to the clamp. If you find you are having problems learning to run the glue without gluing the clamp too, then it might be helpful to keep the rail of the fletch an 1/8" from the clamp edge to avoid gluing the clamp edges. Keep a rag and Acetone handy. Before clamping and gluing the next fletch, wipe the clamps clean of glue.
Also, the front and back of some clamps tend not to place the fletch as flush to the shaft as the center portion of the clamp does, especially with a helical clamp. I suggest doing what I do. Once the fletch is clamped, and before applying the glue, I pull a bit of the front and rear of the fletch from the clamp so that the front and back make good contact with shaft.
Have fun. You will catch on very quickly and find that it is actually fun and satisfying doing your own fletching.