Hi, Rjgfly
Post a DXF file your having trouble with, Use the REPLY button and attach it with Attach option.
1. Mach3 is limited to 500 lines of G-code without a License, LazyCam license will allow offsets, pocketing and turn/lathe features.
2. Hard to say depends on the complexity of your drawings.
3. Post an example of your code.
4. Haven't a Clue on that one.
Thanks, Chip