Some answers to some of the questions, but not necesarily in the right order. I have an old Myford Super 7 on which I do all my turning. I have adapted blank stub arbors (2MT) to carry wheel blanks and also Thornton's cutters. After turning, the complete arbor is transfered to the dividing head on my miller (Centec 2B), which is also 2MT, so no loss of concentricity.
The dividing head has been fitted with a stepper motor, itself driven by a DivisionMaster black box, so any number of teeth can be cut. And away we go.
The other machine that I am still learning how to use fully, is a little Taig Bench miller. This is CNC controlled, so I now machine all the crossings (spoking in US) and it save me all that 'filing to the line' which I now find harder and harder as my eyesight gets worse.
When I cut the internal teeth of the anulus gear, I needed to make a cutter frame (to pass into the bore) that would be stationary while the table of the miller traversed to cut the teeth. I mounted it on the quill of the vertical head while driving the cutter spindle with a belt from a pulley in a chuck in the horizontal drive. Again, the chuck carrying the turned blank was transfered to the dividing head as it has the same nose fitting as the lathe (very useful facility!). I'll try to add some pictures of the cutter frame, cutting the internal teeth and crossing out a wheel. The multi-tooth cutter is mounted eccentrically on the cutter frame spindle so as to precent a single tooth to act as a fly-cutter, suitably counter balanced.