For the speaker position, as in the graph. A quadraphonic setup. You’ll send 4 channels. 1&2 mainly in front and 3&4 in the back. According with the room size you could add intermediate support speakers. You need to have a plan of the concert room with measurements. For the microphones. For the sound capture (piano and others) mainly dpa. For the aerian mics (room amplification), it is up to them, with what they have at their disposal. You’ll need to receive the two piano mics mixed on channel 1 (card input) and the other instruments mixed on channel 2. If you need more information, let them know.