Old setup from the ye good olde EMC2-days.

As topic says I have a box running a very old emc2 version, wanted to upgrade to linuxcnc (nowadays it probably even uses the LTS-version that had my touchscreen working flawlessly (hacked together a fix so that it worked, not very finetuned though.

Shortly, to make things simple, what do I need to backup to keep my machine setup?
I have the basic setup for the steppers etc, nothing fancy there, gamepad setup according to an old post/video of I recall correctly as pendant and a custom hal for it or something (its been a while)

Would like a total fresh reinstall to get things minimally with issues.

Used to have it possible for the machine to turn my spindle on and off during machining to in the beginning but lost that feature not sure if issue with my PP for vectric or what Thinking newer version of linuxcnc might have better guidance on which pin It is triggering etc.

Sooooo backup?

Almost always saving the config folder to a USB stick will do, but since you have other stuff there for the gamepad, that might not work. I did say "might" as again most probably it will work if there are no extra components that need halcompile to install them again, even if they do, that should be fairly easy.
There are several ways to do or test things without messing with the old installation:
Get the stretch version of Linuxcnc ISO from here
linuxcnc.org/downloads
write it to a USB stick using DD form Linux or win32imager from windows, insert it in the existing computer and boot from it, make sure the BIOS is set to boot from USB devices.
Start the Live session, and open the existing config folder, right click on the ini file ( whateveryourmachinenameis.ini ) and choose "open with" there is a tick with "use custom command" and write beside it linuxcnc , press enter, and if the Linuxcnc loads try to move the machine, if it all works, you owe me a beer.
Before doing any of these steps, do make a backup, usually in ~linuxcnc/configs/nameofthemachine, but in your case it might be ~/emc2/configs/nameofthemachine.