Bed leveling problem
To address the firmware problems, Download a fresh edition of Marlin 2.0.x and configure the Configuration.h and Configuration_adv.h yourself. Others' configurations are expecting fully stock parts, and will not be compatible with your system.
Your main problem seems to be in your Probe Z-Offset. To get good level, you need to calculate how far above the bed the nozzle is when the probe triggers. The BLTouch height screw is NOT for Z offset adjustment, and the Z-offset needs to be set with M851 in Marlin. See https://marlinfw.org/docs/gcode/M851.html for more detail on how to do this.
Additionally, the Z-MIN switch should not be connected when using the BLTouch, as it IS the new Z-MIN sensor.