ESP8266 ESP-12 configuration using SPI

I want to use ESP8266 ESP-12 as slave. For accessing 2MByte per second, i need to communicate with ESP-12 using SPI.
So, my questions is:

1- Can i configure and send/receive data only trough SPI pins(and leave unconnected UART Tx/Rx pins)?

2- Is the configure could be done using AT commands like this serial interface? :
AT+CWJAP="your_network_name","your_wifi_network_password"

AT commands work only over UART

12F can be wired over SPI