Hi,
yes, the boss style (center negative) could not be directly connected to the Arduino DUE board cause this
last one is center positive.
I also use a diy adapter to connect a boss adapter to the Arduino Board but it is not the most elegant arrangement.
Looking at the Arduino DUE schematic, the Vin pin goes to the same point that the Arduino power supply adapter. The Arduino Jack is reverse polarity protected using a diode (D5) and also this diode will help to use only one source of power in the case that you provide energy through the Vin pin and the Jack connector.
You could even go further; instead of wire the +ve and -ve to the pins marked "VIn and GND, you can wire +ve and -ve to the Arduino power supply jack (the pins are big are very easy to access and solder on the bottom side of the Arduino PCB). Doing it like this the diode D5 will always protect you from reverse polarity, so if somebody plugs the wrong polarity adapter all will be safe.
So yes, in theory you can connect a boss female jack in a box and connect it to the Vin and GND pins of the Arduino Board and all will work together.
couldn't source the correctly dimensioned pots or jacks locally
We get all from Mouser, in the Bill of Materials of the project you can see the part numbers if you want them.
Along those lines, any suggestions on how to setup an off board reset button? I'm thinking a momentary switch wired to the "reset" pin that is under the output jack and the near by 5v GND pin.
Yes the best way is to connect an external button to the reset pin of the Arduino board (next to the 3.3V pin)