It is possible to execute the North American format in Australia effectively if they can somehow merge the two.
Sunday: Daily Show (covering the weekend)/Live Eviction (featuring Head of Household)
Monday: Daily Show (Task Part 1/Nominations)
Tuesday: Daily Show (Task Part 2)
Wednesday: Daily Show (Task Part 3/Power of Veto Comp & Ceremony)
Thursday: Daily Show (Task Part 4)/Confidential
Friday: Daily Show (Task Part 5 & Results)/Friday Night Live
That has it on six nights a week. If they can keep the tasks (which is a good part of the show for most people), they should be fine. If it devolves into a constant strategy-fest, maybe not.
As for Mike Goldman as narrator and Leon Murray as Lead Deputy Big Brother.... yes, yes, and yes! As far as host goes, why not a former Housemate like Benjamin Norris? He ticks off a lot of the boxes you'd want in a host, and he'd provide valuable insight into what goes through an HM's mind.