CONFOR,
Sounds like an interesting trip, apart from avgas avaliablity, one of the harder things is getting your paperwork and procedures in order for Darwin.
Australia is a beaureacratic nightmare to operate into, compared to Africa, especially regarding quarentine procedures.
Ive seen the Darwin quarentine police send aircraft back to their points of origin (Jakarta) because of minor procedural infringments, like having cargo on a wooden cargo pallet instead of a metal one. You may not bring any organic products into Australia from another country.
Your aircraft will need to be fully decontaminated according to Aussie quarentine rules at last point of departure before Darwin, there are 2 spray tins (red and blue) that need to be used appropriately, only avaliable from the Aussie querentine police in Mainland Australia. You will need to get these beforehand somehow.
On arrival in Darwin you may not even shut your engines down untill the Quarentine officer has given you the 'thumbs up'. Only after you held up the red and blue spray tins for him to see. You may also need his permission to even open the cabin door, depending on what sort of mood they are in.
Infact, corrupt CAA officials in Lubumbashi are more welcoming to aircrew, than HM Quarentine officers in Darwin.
Make sure your handling agents in Darwin are on top of their game to avoid dissapointment.
Also be prepared for very different ATC procedures in Aussie compared to normal ICAO countries.
There are some Saffers operating into Darwin from East Timor who would prob be able to give you better heads-up if you can make contact with them.
Executive Turbine of Lanseria has that contract they could steer you in the right direction.
Good luck
Max.