Rong Fu JFC-500C Mill/Drill Conversion

I am going to buy a Rong Fu JFC-500C Mill/Drill I have also seen it
called an RF-500C; here is a link on the website for the JFC-500C:
http://www.rongfu.com/En_ProductDesc.asp?
Price_Version=P&pidno=200112190043

It accrued to me that I might be able to put stepper motors on the
X/Y axis so as to make it a CNC mill and perhaps later on the Z axis
as well. I was wondering if anyone had any suggestions as to what
type stepper motors would be suitable for a machine of this size.
Would the motors have to have encoders fitted? Also I would need to
get control circuitry that can pass enough current to control the
motors without burning out.

Could I use the original lead screw arrangement or would I have to
fit ball screws instead?

I will also need to find out what software I could use to get my
CAD/CAM drawings into finished machined parts? Presumably I can
import a drawing or model and the software will generate the correct
G-Codes or whatever based on the cutting tool used?

I was looking to spend no more than say £1500 ($2400 US) on this
project. If anyone could give me some suggestions on what parts
and/or software might be suitable I would be most grateful. ( I
already have a spare PC to control the motors etc.)

Thanks

Steve B.