Hi Garth
Unless you are targeting specific species, what you do in the Murray will work just fine. All you need to do is change the bait to salt water bait...not too many salt fish like earth worms.
Your basic cod or yellow belly rig will be fine to get you going. Prawn or pilchard are the standard basic baits for general fishing. If you go for pilchard get salted or brined if you can, simply because they last longer in the sun.
Safety is an issue if you have little or no knowledge of the sea. If you have never been to the coast or fished coastal water before it would be a good idea to just sit and watch the water for a few hours. That will give you an idea of how it moves. Remember, unlike the river, the sea is tidal ! The way the waves are hitting now will be different in an hour from now. The golden rule is never turn your back on the sea.
itsaboat mate...Life is just a boat and then ya marry one !