POTS are all 10k log either dual for stereo use or dual concentric stacked mono with odd on top. 1,2 3,4 5,6 7,8.
BUSS resistors will usually all be 10k for SUM8 or most mixers or 47k for API.
SUM resistors are only needed if mono linking AUX1 & AUX2. Link over is not using mono linking.
SUM resistors would be 820R with BUSS 10k resistors so opamp like LME49470 or LM4562 or NE5532 used that can drive 500ohms
SUM resistors would be 680R with BUSS 47k resistors so opamp like LME49470 or LM4562 or NE5532 used that can drive 500ohms
(Like in our Palpigrade uses which just plugs in to the 16pin in 1-8 headers)
AUX 2 pin headers can be wired to simple on / off switch or linked over if not needed.

Notes and Errata Ver 1 PCB.
Sum resistors or links need to be fitted crossed as shown below.
Resistors can be fitted one on top and one below.
AUX1 & AUX2 switch headers are marked in reverse.
