Hua Hin is a very good immigration office. You will need to report when you have a lease from your landlord. You do not need to report if you are away or leave the country. I used to go back to report in when I returned from Oz but they always ask "Are you still in the same place?" I say yes and they tell there is nothing to do.
I'm an Aussie that had an O-A too. Just do the border bounce. You'll get a free year with no hassles. Don't forget you need a re-entry permit if you leave during the second year.