Help before purchasing a K40

In my effort for changing from my current 40w Laser Diode machine to a K40 machine, I have a few doubts.

-K40 is on my budget, but the bed size is just… enough. Is there any alternative (not much more expensive) for 30x40 cms size?

-I love LightBurn, and have read that there is no direct support, but you can purchase an alternate motherborad. Not much more money to spent on this (at least, currently), so… can I export LightBurn proyects to any format, so other software can burn it?

-Currently I use an external controller on my CNC machine. How can I use the K40 without a computer? I have not a computer to spare with the machine, so I had to buy an old computer for this… K40 350€, old computer 300€, so… the K40 is 650€ for me… any better alternatives for this money? (although I would love to stay on 350€ budget…)

-To cut 3mm MDF I use 70mm/min, and my proyects take around 30 minutes to burn… 30*70=2100 mm cut per sesion. What is the cutting speed of a K40? (so I could math my 2100mm to know the estimated time for a K40 to cut the same proyect).

Agai, your help is greatly appreciated.

I bought my K40 two and a half years ago for 300 Euros on Ebay. In addition, I have invested in a cooling machine (which I will also use when I change my K40 to a larger machine) After I have changed the original controller to a Mini-Gerbil (approx. $ 90), made a usable machine bed, an air nozzle with a small fan and installered an external exhaust the machine was ready to produce. I have been lucky with my K40, no electrical problems (except the original extraction) and mechanically / optically I am also very satisfied.
I mostly work with cutting items in plywood, MDF, HDF and acrylic. From 0.8mm to 4mm plywood and M/HDF and acrylic often 6mm.
I cut 3-4mm BB-plywood with 650-750 mm/min, it also fits roughly with the other materials, 4mm slightly slower, all depending on the quality of the material. Acrylic 8mm, here I use 2x 300 mm/min to get a nice flamed surface. I also cut a lot of 0.8mm and 2mm plywood here I use about 1000 mm / min.
Below the line, I’m very happy with my K40, which is also why I can not bring myself to finally buy a bigger machine - yet.

My biggest shortcoming of my K40 is the bed size, unfortunately it is only 320x230mm large.

PS. the cooling machine is not absolutely necessary, but if you work a lot with the machine, you will quickly get tired of changing cooling / ice elements in the water tank.

I also have a 5.5 Watt Eleksmaker in my workshop, but use it only very rarely.

If I can help with further information or pictures please tell.

Good Night