It's not for nothing they put their signs up warning you not to camp in certain places. Bob and I got kicked out of one spot with a warning that it would cost us dearly if we spent the night where we were (near the estuary).
There's a wise adage someone on the road once told me; "Stay just outside the town lights". We were discussing free camping at the time and I've found that to be sage advice.
You get hit with a substantial fine should you transgress.
When you visit Kalbarri you should be aware of the extreme heat and the sun. Make sure you always have enough water with you when you go for a hike and apply lots of suncream.
Another annoying feature of the heat is the amount of flies, especially when you're having something to eat. The best thing to do is to stay inside or try to get used to it (which is VERY hard)
The only danger area I came across was when sailing in and out of the river mouth, it can be very rough as there are cross currents and the black rock which have to be negotiated, swimming and surfing definately a no no.
Be careful if walking out on the reefs, there may be the occasional blue-ringing octopus in the area. Also be aware of rising swells if fishing on the beach or rocks.