If the filaments feature is used, it is recommended to put this code into tpost*.g to ensure the right filament parameters are set.

What code? Might have been quicker and easier to understand if you’d wrote “M703” in place of “this code”.

If you put “C1” in the M581 line in config.g, it’ll pause when you short the pin to gnd. So if you wired a button to Pin 4 on the expansion header, you’d want “M581 E2 S1 T1 C1” in your config.g. I’m not sure about the joystick.