1. While 80 minutes is plenty of time in OOL, that will put your friend in a very tight situation because at T-30 check in closes for the domestic QF, which means provided JQ lands on time, he'll have under 50 minutes to get through the masses at immi, grab the bag, clear customs/quarantine (and the new 'special security' queues if your friend fits a certain criteria which can take anywhere from 10 to 60 minutes alone). So short answer is no just to be safe.

2. Baggage must be claimed on the way out in OOL then checked in with JQ as interlining between QF dom and JQ int only is possible if both fligths are on the same ticket. MCT on the way out is 100 minutes but that's cutting it too close with JQ's strict check in times. Best to allow 2.5-3 hours, again to be safe.

Having said the above, aren't there good fares on VA with alternate times for OOL-SYD and vv that could work out better than QF?