What Size Servo Motors?

I am new to the list and have a couple questions and need some high
level guidance. My plan is to convert a mill (which I haven't bought
yet) to CNC. The mill will either be an older Bridgeport type or a
smaller bench type. Thanks in advance for any help.

1) If I go with servo motors because of the higher torque at speed
and the continuous feedback. A) what size servo motors should I be
looking for? Are there any other things to look for, or keep in mind
with a servo setup? Are there any good sources for used ones?

2) Am I assuming correctly that the Harbor Freight import type of
bench top mills are significantly inferior to the older models? I
don't really need the size of a Bridgeport and have space
considerations. Any recommendations?

Mark