I'm not sure what a e240 stepper motor is, possibly nema 24 size? Normally on a mill "a" is a rotary (4th) axis and a vertical axis is "z". If the machine came with a rotary that's a nice bonus.
I have a decent size manual mill as well as a couple of smaller cnc mills. Manual mill with a DRO covers the most common milling operations. CNC shines when the geometry includes arcs and angles. The type of work anticipated will decide whether cnc is worth the effort. With the number of cnc conversions done on these mini-mills there must be a world surplus of hand wheelsno electronics or other cnc stuff came with it. I would like to have cnc capability, but not essential. is it best path to go back to manual and purchase (or make) handwheels or go forward with cnc and purchase stepper motor drivers and associated electronics.
Uhm..maybe. Also Grbl may be of some interest. If you dabble in arduinos you'll find a cnc conversion pretty straight forward. Electricity and me don't get along.can I do this with some of my ardunio stuff?
Some pictures would help people answer. Unfortunately you need some posting history to allow attaching photos.