Power Line Decoupling in Eurorack
Depends on the application. If the output is with respect to GND I would use only C3 and C4 100nF to GND (also you may use C1 and C2 for extra bulk), otherwise if the output is with respect to either supplies then only C5, but not all toghether.

Place them in the PCB close to the pins and traces as short as possible.

To extra improve EMC you may the fanout should be:

OPAMP Pin --> thicker trance --> capacitor Pad --> thinner trace --> via (to the power plane)

Consider the width of the traces to be able to carry necessary currents.