40W Chinese Laser Conversion questions

[wrench]

Good Day, I have a 40W Chinese CO2 Laser and see you sell both a 4-axis and 3-axis Control Board.
Can you explain why they both are sold for the Laser, and which one would you advise for a conversion from Moshidraw to Mach3.
By changing from the stock Laser set up to a Mach3 set up, will my Laser be capable of engraving with different shades like a photograph, or
will I only be able to use the Laser as a Cutter. What I mean (in case I am not explaining clearly)is, can the Controller change the lasers power output/intensity.

Also, on E-Bay, I see two 3-axis Controllers with one card using a small fan on top of the heat sink. Are they both the same other than the fan being installed
on the one board?

I have some lower torque Stepper Motors(around 205 in/lbs Holding power)and I wonder if you use the stock Steppers or use other Steppers. If you use other Holding Power Steppers, what would a good Stepper to use.

Lots of questions I know but I have not seen this done before and I have had this Laser for a good two years and it just sits here collecting dust.

Wrench

[wrench]

I would imagine that more Controllers would be sold if the questions were answered!
I also asked questions through E-Bay and again...no answers.

I looked and considered purchasing one or two, but if I can't get answers now, what would I expect AFTER I bought and had questions?

Adios................