Hi again_Kodak_:
First off, you may not need to retrofit the machine at all.
If it is in good shape and has all the bits intact and working it can take commands and turn them into instructions to the axis motors telling them how to move.
Since you have discovered it can understand a variant of G code, you just have to know which flavour of G code it can understand and then give it that code.
That is the function of the CAM software and the post processor together: the CAM system translates the graphics on your computer screen to universal instructions that your post processor then translates into the G code dialect specific to your machine.
All of the things you reference in your post are contained within the logic of the machine's control.
You need to tell it when you want to do a toolchange for example, but the control knows how to do that once you tell it that you want one.
There is no need for you to know the details of how it does that unless something is broken and needs to be fixed or ripped out and replaced.
So I encourage you to find out first if you have a complete intact machine.
If you do, all you need to do is figure out what kind of G code it wants, and how to tell it where the job origin is, what all the tool heights are relative to that origin, and what order you want the tools to be presented to the work and what they are supposed to do.
The CAM system does all that, together with your setup and tool touch offs.
Freedommachine made a great suggestion to try to find a sample program you can run and also pick apart to see how it was constructed.
That will take you a long way toward success.
Cheers
Marcus
www.implant-mechanix.com
www.vancouverwireedm.com