gbagua wrote:When do temperatures start to cool down in that area of NSW. Don't want to carry any warm clothes for night time; I'm still thinking in summer mode.

It's aleady started cooling down. I hope to walk it towards the end of the month. You can see past weather observations here
http://www.bom.gov.au/climate/dwo/202203/html/IDCJDW2149.202203.shtml Just scroll down a bit to see month by month.
Still warm/hot during the day, but there is normally a sea breeze, so should be comfortable most days. Ocean temps will start to cool off in May if you want a swim.
Clothing wise, I'll be wearing shorts and t-shirt (and sun screen) and carrying a long sleeve shirt, wind pants and a rain jacket. Sleeping: tent, mat and 10C quilt. Anyway you can see my full gear list here
https://lighterpack.com/r/86dazy. This is the same setup I used in October walking from Coolangatta to Yamba.
I'm not bothering taking any cooking gear because I'm planning to walk past Red Rock and there are towns all the way down the coast.
Best tip I can give is tape up your outer right heel for walking the beaches if South Bound. Otherwise you'll almost certainly get blisters.