3. What kind of Computer do I need / use?

The selection of a computer in large is decision based. If you intend to use a computer for both the Design System and the Milling Processes then you will need to look at the software requirements of each of those. So you need to look at the System Requirements for systems like G Simple, Carbide Create and whatever else you may use. So that is one set of data points.

Next would be the CNC Milling Software such as MACH III or GRBL. That would be a second data point. Now GRBL is not a Gerbel (a member of the rodent species) but you can find out more about this cutting software here GRBL . Basically it is code designed to be Arduino friendly. MACH III unless it comes with the machine must be purchased and you can find out info here MACH III . The cost is about $175.

Then we have the issue of Windows versus Linux. Up until about two years ago (and aside from the Raspberry Pi3 forays) I never had a full blown Linux machine. I now have three and they are all running Linux Mint. So as long as the Design and Milling Software can run on Linux then there is no constraint to that approach. Most of my CNC stuff however is on Windows machines.

Now a twist here. Many of the small low cost CNC Milling machines often called routers that use GRBL have an Arduino built into the control system, That means you can run the mill locally or it can be run from an external computer such as a laptop.

By and large most computers today are faster than 1 GHZ and most have 4GB or more of RAM. That is probably the bottom edge when using a remote computer for milling.

One other strange carry over requirement -- many of the machine controllers use the parallel printer port for the IO to the Machine controllers. So you need to look at the computer CNC Milling machine interface to be sure you can connect the computer to the Mill.

On my CNC Mill (now almost 10 years old) it uses a Windows XP Pro computer, with the parallel port interface and the MACH III cutting software. It is a 1.8 GHZ machine and has 8 GB of RAM. I also have G Simple on this machine and KCAM for the .dxf to G-Code conversion. KCAM is no longer available. There is much to be said to having the Design System and Milling system on the same computer. Many times I will whip up a board and cut it -- and the total elapsed time is maybe 10 minutes all done at the CNC Mill bench.