Question I'm a newbie, I need a little push forward.

I have started my sim simulator project first, and im happy to announce that i did the first steps. (literally)

I made a 4 leg 3DOF sim simulator mini project, to test the software side of my idea about my rig, and i started to solve the problems.
Now im writing here, to ask a few tips and guidelines where to search for continuing.
Im a mechanical engineer, and im working in a workshop, so the technical (mechanical) implementing is not so difficult for me, but the software IS. So i decided to test the whole software system before the building.
As you can see on the pictures below i bought an arduino UNO, and a CNC shield with DRV8825 stepper driver. My goal is a 2PC system, so i put on the bottom a raspberry pi zero too, to provide later the second PC.
I made a sheetmetal basement for my idea, which contains all the panels i would use, and 4 stepper motors. My first problem was that the motors I ordered and designed to my project is not working with the motor drivers, because the drivers are using higher voltage, that the motor can handle (motors works with 3-5V, driver works 8,2-42V). So for the beginning of the programming, to at least drive a bit a motor, i take a bigger motor for the tests.
I become very happy when i could start the motor with accelstepper.h with the cnc-shield with my pinout list for the cnc shield.

Now im stuck a bit, and thats why im writing to here. I need more info to the continuing.
Could someone help with some arduino code, that starts to communicate with a PC to controll the motors in my layout.
I have found threads which is processing 3DOF 2DOF projects with arduino and DC motors with H-bridge controll, but i didnt found one, which is similar for my ideas. (3DOF, linear actuator with step/dir stepper motor control by arduino) I'm sure, that there is a bounch of topics with the same problems i have, but im lost a bit i think.
Is there an available, accessible, written program for arduino to controll 3-4 stepper motor which are in the corners of the rig, and operates the system by this way?

About my rig layout:
Im hesitating a bit with 2 types of the layout. Mechanically i think it is better to use 3 "leg" but in life i think a 4 leg layout would be better.
-So one option is that i already saw on many pictures, that there is 4 individual motor actuator in the 4 corner,
-and the second idea of mine, that there is 4 motors, but the first two operates as one.
With this layout i would make a "bridge" in front, and connect the frame on a ball joint in the middle.
My opinion, by this way would be easier to avoid the instability of the rig.

So can any one help me for continuing?
Later, when all my setups are tested and working, im considering to start a new thread with the building and the steps of my projets, to share my experiences and documents.

thank all, levente.

Hello!
Thank you for the detailed reply!
I saw a few of @Lebois posts and work later but i didn't pay enough attention i think. Now i started to read his stuffs, seems really usefull. Thanks!
As i see, many simulator, which i inspired on, works with servo instead of stepper motors. As i compared the stepper motors are in a same price with closed loop driver, but the steppers have a higher torque. Why they use the servo drive instead of stepper motor? Is it faster, or more precise?

Both are use the step/dir control, so basically i think on arduino side the program could be the same, so now i will continue with @Lebois writings first now, and Ill read the other threads too.
All in all, thank you for your reply, now i can continue a bit more!