So the PAPIs and the GP are not aligned?
Correct - PAPI is at the "normal" position, ILS GP antenna is much further down the rwy than normal to provide adequate terrain clearance over the ridge in front of the rwy.
You are 'diving' a widebody and aiming at what? 2 reds/2 whites, or 3 reds/1 white?
Yes, with "diving" meaning leaving the 3-deg GP at about a 4-deg flight path angle to pick up the 3-deg visual glidepath (2 white/2 red or 3 white/1 red, whatever's appropriate for your a/c type). If done correctly, the whole thing can be done without sinkrate-warnings and you'll be nicely established - even at groundspeeds in the 180-200kt region. It's kinda fun actually. By the way, all this obviously means that the minima for this approach are quite high.
What are the TCH's at Quito for the PAPIS/GP?
Haven't got the charts handy, but TCH for the PAPI is "normal", for the GP would be quite high.
..............and lastly - who 'approved' this?
Hmmm, who knows. But it's in the books and it's what "everybody" does.