Nick
I did the walk as a 16-year-old highschool kid at the end of 1969. We walked north to Kokoda.
The memories are still with me. I'm sure that you too will find it unforgetable.
As far as clothing goes; think how comfortable you will be walking whilst bathed in sweat and water from the daily rain event. Go for as little as possible. I wore the one set of clothes for 5 days. I also had a light cotton blanket to curl up with at night, sleeping directly on the woven floor of a hut. I distinctly recall the joy of sleeping directly on the flat hardwood floor of an empty government building when we got to Kokoda!
I wore boots purchased from the local army disposal store in Parramatta but no gaiters - they weren't needed as it was track walking only. These days I would make sure that footwear was tried and comfortable but I would still take blister patches and a spare pair of socks.
We ate simply: rice cooked with powdered milk, eaten warm and cold the next day, and yams cooked by villagers. Food was fuel, and I looked forward to whatever there was.
I don't recall worrying about mossies etc. We did not use mosquito nets, but I think that I had a bottle of DEET to rub on. It's a wonder that I've haven't had offspring with two heads
All around me as I walked were signs that whatever discomfort I was feeling paled into absolute insignificance compared to the suffering that the soldiers went through only a quarter of century earlier. I was a fiery adolescent Vietnam War protestor at the time and subsequently maintained an anti-war stance. But my respect for Australian soldiers serving on our behalf was forged during that walk and firmly remains to this day. I wept during the recent ABC documentary on the Kokoda campaign . . . perhaps if you saw it you'll know why.
Best wishes for a memorable experience.