Choosing the right design for woodworking

I'm a woodworker new to CNC interested in building my own CNC router
to make furniture components and cabinets. After immersing myself in
the wealth of info here an on the web, I still can't determine how
much machine I need to do the job.
1) Servo or stepper motors?
2) how powerful of a router motor?
3) what about tool changers?
4) Is three axis enough? - I'd like to turn legs and some carving
5) Why do hobbiest level machines communicate with the PC via
serial/parallel ports, but commercial units use ethernet? Is there a
need for faster data transfer?

I know, I ask alot of questions for someone from the Northwest. BTW,
I did search the archives, and read the faq.

Wayne from White Salmon