The flight crewmembers’ failure to properly monitor the airplane’s flightpath, which caused the approach to become unstabilized and resulted in the airplane’s descent below the decision altitude while misaligned with the localizer course. Contributing to the incident were the first officer’s delay in setting go-around thrust after the captain called for the go-around and the captain’s failure to take control of the airplane after go-around thrust was not immediately set, both of which caused the airplane to come within about 50 ft vertically of an occupied taxiway.