Hello. Sam here. I started a Hobby CNC router a long time ago, Around 15 years or so. I assembled the power supply and electronics, and fabricated the machine, then life got too busy and I never finished it.
Now that I am retired, I thought I would try to get it going. Attached are a few pictures of it as it sits now, I used salvaged ball screws on all three axis, so the pitch on all are different. I am hoping the software can compensate for this when I get it going.

I plan on using this to cut out balsa and ply parts for model aircraft. Travel is approximately 31" in X, 19" in Y and 5-1/2" in Z. Construction is MDF, When I stopped working on it, all that remained was connecting the home and limit switches, making the cables to connect to the electronics and computer, and installing some software.

So, looking at it, I now have a few questions.

First, the home location for X and Y are obvious, front left hand corner. But what about the home location for the Z axis? Two choices, where the bit touches the table, and with the bit fully raised. To me, it makes sense to be where the bit touches the table, so any movement would be positive Z up from there. But is this correct?

Next, software to drive this thing. What would be a good choice for the dxf to g code and the machine software? Free is good, but I have no problems buying some as long as it doesn't get too high (fixed income) My max would be around $200 for all software.

And finally for now, the plans show the limit switches as "per software" I'm assuming that some software is looking for normally open, and others look for normally closed? I need to know what style switches to mount. (unless I install a switch that has 3 contacts with both NO and NC)

Thanks for any help on this.