Quito is not a place for amatures. Yes you do have to abandon the GS (3.2deg) at 664 DH and transition to the PAPIs (3.0deg). That requires about a 1200-1500 FPM initial sink close to the ground to intercept the normal visual slope. Eng out considerations are VERY important considering the pressure altitude and terrain. There are people that make a living picking up aluminum off the sides of mountains there. Quito is usually a special qualification airport for airlines. The fact that you're asking these questions in this forum, in an attempt to get certified, would be red flags to me if I were the FAA.