You can out the arduino into sleep mode pretty easily.
Need these
#include <avr/sleep.h> // powerdown library
#include <avr/interrupt.h> // interrupts library
An easy way to wake up is external interrupt on Int0 or Int1 (low on pins D2, D3).
Set up D2 or D3 as an input with pullup resister enabled, pulling it low via a switch will wake it up.
Not sure what you can do with the transceiver. I only have a transmitter, it doesn't seem to draw much power when no data is sent to it for transmission.
Have to read the transceiver spec, maybe it has something built in. Or maybe add an external transistor to cut Vcc to it.