1. You can probably live without the steppers.
2. Upgrading to PathPilot is highly recommended. The software is much improved over Mach3. I believe that Tormach doesn't support Mach3 anymore.
3. You need to get 3D modeling software and compatible CAM software or a CAM plugin for the modeling software. Fusion 360 can be free. Most importantly the post is well supported for the Tormach machines.