New build with recycled parts on a ridiculous budget 120cm*60cm work area

[Desertboy]

I'm confused where everything goes and how to wire it up. I'll try and explain what I understand please correct me where wrong I normally am lol.

I can see the X, Y, Z & A pul/dir go to the AM882's, the power from the stepper motor PSU goes directly to the drivers not through the BOB.

I think the limit switches one wire to each input and the other wire to the shared gnd? I need 2 limit switches for my Y and 1 for my X can I reconfigure the Z axis limit to be my 2nd Y? I want to set linuxcnc up so it squares the gantry. I'm going to use microswitches for now but I might use inductive sensor instead do I simply find 12v for the sensor elsewhere and wire 1 wire to the Axis input and 1 to the GND?

Tool setting is this the input you would run a probe to? Again is it a shared gnd?

Emergency stop run my stop button to it AND the outputs from the AM882 for stall protection.

I believe I don't need the enable pin out

PWM must be pulse width modulation but for what?

PC GND and the 2 PC 5v outputs where do they go?

the spindle on/off and 0-10v are self expanatory but the 12-24v is that an input for driving the board? If not what is it used for. I thought the board was powered by 5v from the USB socket.

What does the relay jumper do?

Thanks
Desertboy