Got to love the comments from pax that FA's looking out the window = panicking. Errr, how do they think the flight crew are going to get an accurate report without 'eyes in the back'? (yes yes I know there are cameras etc but I don't think they are clear enough or positioned correctly for this sort of thing)
As for engine change, I don't think Sydney on ground in springtime will be an issue... recall an article awhile back about someone in EK engineering creating a custom 'tent' to cover the area so they could work in adverse conditions and get urgent maintenance completed. Guess they can do the same here if needed.
QF equipment is different and not the right sort required for engine issues, about a year back a flight out of Sydney needed a component replaced and while QF had the spare the equipment required to fit it was not compatible, or so their engineer told us.