Finally got the damn thing working again - issue was pin assignment in RF24 radio statement

For reference, pin numbers are like so:
VCC - 3.3V
GND - GND
CE - GPIO22, pin 15 (use RPI_V2_GPIO_P1_22 in RF24 statement)
CSN - CE0, pin 24 (use BCM2835_SPI_CS0 in RF24 statement)
CLK - SCLK, pin 23
MOSI - MOSI, pin 19
MISO - MISO, pin 21