I know that the LED Green and Red pin is used to show the IMPs status, but can they user controlled without damaging the pins?
Well, they are outputs dedicated to be used solely by the imp-002 to indicate status as you mention, so really can’t be ‘user controlled’. You could conceivably hook them to something besides LEDs if you desired, but again, they are just used to indicate the status information.
Are you asking this because you ran out of pins to use? You can buy an Imp002 with double the pins, or use a serial to digital output latch (separate IC chip) … 1 pin (uart) to 8 digital outputs (or 16, 24, 32 or up to 64 outputs by using multiple IC’s).
Texas Instruments: SN74LV8153N
Mouser Electronics Cat No. 595-SN74LV8153N (approx $2USD)