Apart from understanding the Arduino's code ... on digital pins D10 to D13, and the I2C/TWI pins are on A4 and A5. Meanwhile, on the Micro, the SPI pins are on pins MO, SS, MI, and SCK.

There are some things the Arduino can do that the Raspberry ... you can access one UART (pins D0 and D1 as RX and TX), one SPI (pins D10 to D13 as SS, MOSI, MISO, and SCK), and one I2C/TWI ...