Also , just some general questions if you can answer. My LPT is labelled LPT3 but of course in "ports and pins" there are "Port1" and "Port2" options, does that matter ?
No, Mach doesnt care what Windows calls the port, all it is concerned with is you have the port address entered so that it knows where to look.
Is there a prefernce to use ?
You can use any but probably best to set up as Port 1