EMC, the basics...please

Group,

From semi-lurking for a couple months I've picked up a little info on
EMC, not a complete understanding, though.

Could someone please summarize the software and hardware necessary
for implementation of a servo (and maybe stepper) system. Like how
does the EMC-resident pc communicate with the servos, serial,
parallel port, add-in card, whatever. Is the machine control panel
the pc's keyboard? How is I/O handled, spindle motor, coolant pump,
feed rate override, etc?

Any rough estimates of costs based on something like a 650oz in
system for a medium size knee mill, assuming a CNC-ready (ball
screws) machine and purchasing new servos and amps as opposed to
surplus stuff.

From my casual lurking, it's hard to tell if there are any EMC
systems out there currently making parts. Are there? If they are
making parts, are they production quality, reliable systems or more
hobby type?

thanks,

Doug