Yes and yes. You will need to swap the fuel pump wire to the 'non immobilizer' pin as per the wiring diagram and switch the red and white wires on the cam and crank sensors around. There's info on how to elsewhere on this forum.
Other than that it's straightforward and worthwhile.
On 99/00 WRX & STi the AFM and injectors are identical. (not so on 97/98)