Hi,m0j0
A1&A2:You may use two the Grove - Serial Bluetooth connected with the two
arduino,and they will use the D0/D1 pin seeedstudio.com/depot/grove- … th=139_142
So you can try to enable the communication between the two arduino boards.
A4:Yes,you can use the open pins.D0/D1 is RX/TX(serial port).
Regards,
Frankie