Yes, it can be changed by editing the I2S code. It's been discussed before. Maybe you can find some of those old threads by search?
For transmitting signals farther, the key to success involves using cables with well known characteristic impedance, and matching resistors. Usually CAT5 or CAT6 network cable and 100 ohm resistors works pretty well.
For really long distance, using a fully differential signal like RS485 makes a huge difference. But that does involve adding chips to transmit and to receive.