Beginner's Mill/Drill to CNC conversion questions

In my search for ways to get a 3-axis CNC mill for
under $3000, I came across this page.
http://www.homecnc.info/cnc-main.html Reading that, I
believe I can actually obtain my goal. However, I
have many questions still.

I would like to use a mill/drill that has a dovetail Z
axis, but if I cannot afford one I will get the same
Enco that was used in the above webpage.

1. Once I purchase the Mill/Drill and computer, how
much more will it cost to convert to a 3 axis CNC?
2. I would like a machine that will give me 0.001"
accuracy. Can I expect that from this type of a
setup?
3. Will I need to install ballscrews, or are they
just highly recommended?
4. Stepper or servo motors? and why?
5. I am trying to get a mill/drill with a dovetail Z
axis. would it be more difficult to convert this type
mill?

I'm glad I've found this group. there seem to be very
knowledgable people here. I'm still reading through
the FAQs and Archives. any advice or tips you could
give me would be much appreciated. Thanks in advance.

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