SparkFun VR IMU Breakout - BNO086 (Qwiic) SEN-22857

Qwiic System
1

the BNO086 IMU has three possible interfaces (i2c, SPI, UART). I wish to know:

1 - which is the fastest interface among the above

2 - It seems to me that the communication over the UART port is not implemented into the Sparkfun library