Welcome to Flyer Talk campo Steve

You have to disembark, take carryon with you and go through security. Australia has liquids rule so don't bother getting liquids >100ml on departure in DXB.

When I passed through BNE a couple of weeks ago international transit was closed off so as to ensure all pax go past the thermal cameras. It may or may not be reopened by now (I'd assume so otherwise they'll need a much longer transit time to cater for all the through pax). I've had international transits at MEL & SYD more recently and at both those airports international transit was open.

SYD & BNE (can't remember for MEL sorry but probably also) have a nice EK lounge near international transits.