I take it these new aircraft are nextgen?
Yes.
Is there direct entry to the Q400 or is it seniority?
Depends on Sunstate or Eastern, at the moment they are recruiting straight onto the Q400 in some ports. If Eastern vote up the new EBA then you can expect to be placed on either a 300 or 400 as required by the company.
Any information on Brisbane base? Typical sectors a day? Expected progression time frame from F/O to CAPT?
I cant help you with the roster, however they do seem a little short of Capts. so if you have the required minimum then you could possibly jump a few low time pilots for command. 2-3 years maybe in Sunstate? 3-5 years in Eastern? This number changes regularly and I have seen it at 18months out to 10 years.
At Sydney you tend to fly either 5-3 over-nights or a 4 sector day shift (SY-CB-SY-CB-SY). Overnights sign on around 1000-1300hrs, and sign off at the same the next day. Day shifts tend to start any time from 0545- 1400 and continue till 2200ish.
None of this takes into account contingency flying.
Please note Sunstate (BN-CNS) is different from Eastern (SYD-MEL-MQL), and to move from one to the other requires your resignation.