probably don't need five coats each.
I have a wind-proof fleece which I wear most of the time. My knee length wool coat which I did wear for about three months last winter but haven't needed yet this year. And a rain jacket because I've never been a fan of umbrellas.
I only ever wear my hat/gloves if I'm going to be standing around outside for a while, e.g. winter evening BBQs, camping, walks along beach in winter.
I wear my leather winter boots here for work, as I have poor circulation and otherwise can't feel my toes.
Remember if you're looking at weather charts, that the times you'll need the coats are in the evenings/mornings, so you need to be looking at the minimum temps, not the maximums. It does drop to single figure minimums in Adelaide so you don't need your snow gloves/boots, but some form of coats/gloves/hat are probably needed.