On the EMB170/190 thing, NJS have done extensive research on the little jet over the past couple of years and whilst I do not know all the details, it is far from being " a great a/c " for the WA routes, hot/high performance and tyre pressures being 2 of the more major hurdles.
The 717 is also a far cry from ideal but I think they are cheap(ish) and QF might be tied to them for a while, also they are probably working on the fact that its a 115 seat a/c that will be carrying 60-80 pax alot of the time. ( slightly off topic but relevant to the
VB EMB rumour )