The custom feet option is for you to decide between the black, gold silver, metal feet/spike vs the standard rubber, IIRC.

The bi-amp input is strictly your call, I would put them in as it doesn't hurt anything and opens the door to more prospective buyers, fickle as they are.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70