re questions about tool form.
Fly-cutters skim, so avoid a too-negative leading edge that pulls into the work. The face does most of the finish shearing, a radius or angled leading edge 'roughs' stock a few turns ahead of that.
A successful turning tool is not too far from a good fly-cutter.
As a side note.
Occasionally, I need minimal tool marks in a recess. I grind 1 flute off a new & proper diameter 2 flute end-mill.
Voila! Mini fly cutter.