Hi Ben,
Good luck with it, I have a MY15 Swan Outback bought from new. Love it.
1. I reckon go new, then you get exactly what you want. Used examples can be pot luck what you get.
2. Jayco (in Sydney) has sales around the Rosehill camping show. But really only getting a few items.
3. I found easy enough to negotiate. For a camper plus options that cost roughly $34-35k retail you'll get closer to $32k or so driveaway. Decent price drops.
4. Options I got were: Bed fly's, Bag Awning, awning walls, bed end garage, Fusion CD player, roof racks.
Main thing I may have changed in hindsight is a fiamma awning rather than bagged, but that depends on time spent at one place. If lots of overnighters, then fiamma, but longer camping means bag awning becomes worth extra set up time. Other item to consider for me would be a water heater, but we don't shower at camper so a jug does us for washing up etc. How often are you camping off grid, as may need second water tank? May want second gas bottle too.
5. I easily push mine around on flat ground.
I also reckon go for the Outback model as they seem to hold value better, and are more versatile in that you can camp virtually anywhere due to better ground clearance. They also look less grey nomad.