What is it about the air in Australia that makes it different from the rest of the world? Why is it that every time an employer wants to introduce a new type, they must have pilots with appropriate time on type? It seems very odd to me that types such as the Electra, B707, DC9 and B727 were all successfully introduced without accident or incident, but an ATR72 or B777 requires the importation of current-on-type pilots.
I can't tell you when things changed but it isn't any different, airlines the world over will get contract pilots/trainers in to introduce a new type to their fleet. Where the airline is large/rich enough they will engage another airline that operates the type to provide line sectors to give their pilots experience on the type. Where the type is a new aircraft they will find people/training for the closest comparable aircraft (eg 777 for 787). I doubt they do this because they want to but because their insurers, financiers or lessors insist on it.
No, because the list you linked to is the SOL which shows the occupations available for temporary graduate, independent or family sponsored visas.
The list of occupations eligible for a 457 visa is found on the Consolidated Sponsored Occupation List linked previously by Biggles.