Does anyone know if the three axis software can be loaded onto a two axis machine?

A friend recently got a 1995 two axis EZ TRAK and was interested in using my system 1998 reload diskette for his machine. His mill has a hard drive installed.

Are there any advantages/disadvantages in using a later version software?

What were the major changes they made in the software?

There were versions even later than mine. What advantages are there to upgrading to the version sold by EMI? Was that the last version Bridgeport used in their 2000 machines?

Next question: Does anyone know if the 3 axis upgrade kits are still available?

Thanks in advance.