Easiest way to mate a motor and collet?

You mean like these. Check out Perske.

Are you re-inventing the Dremel?

What size drill are you planning on using? Would it be possible to use a flex shaft adapter with a drill chuck on the end of it? What about re-machining the end of the motor shaft to the suitable Jacobs taper to mount a drill chuck? I have done similar machining to a 20hp gas engine. We needed to change it from a straight shaft to tapered for a new style of clutch. I did this without taking the crank out of it. Your situation would be much easier to do. Simply align the shaft parallel to the spindle and set your compound to the desired angle. Turn on the motor and hand feed the cutter.

will the motor have enough torque to drill the holes??? typically the gearbox is not only used to reduce speed, but also to increase torque....

Small bits use a speed increaser, sometimes over 10k rpm.

Guest--

Many motors are made with or can be modified to have a threaded shaft. You will find them typically used with swimming pool pumps (in a NEMA 56J frame). 4-pole types (1725 RPM @ 60Hz) are not as common as 2-pole types, however. You could mount a chuck or collet holder to this type of a shaft. In doing this, have you considered the problem of how the drill bit is going to be moved towards or away from the work?

--JMM