Hey Randy,
I can answer only a selection of your questions.
If it is not collected, probably. And as some people reported, it also tends to adhere on the rails too and to accumulate at home position, thereby changing stall homing position with time.
But generally wood dust should never fall down or fly around. Wood dust is harmful, cancerogenic, dangerous. It should entirely be collected by a powerful dust collection system.
Probably not. But you should be aware that with the 65 mm mount, the spindle will not clear the stepper so you have limitations on spindle length and/or spindle position in the mount. With the optional 80 mm spindle mount, the spindle clears the stepper so you don’t have this limitation.
Also some people had issues with hairline cracks with some 65 mm water-cooled spindles.